Method and device for transmitting or receiving information about links in wireless lan system

ABSTRACT

The method executed in a wireless local area network (WLAN) system, according to various embodiments, may comprise: a step in which a reception station (STA), which supports a multilink comprising a first link and a second link, receives a target wake time (TWT) element via the first link, wherein the TWT element is received via a beacon and includes information for TWT period configuration for the second link; a step in which the reception STA configures a TWT period for the second link on the basis of the TWT element; and a step in which the reception STA communicates with a transmission STA via the second link within the TWT period.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/269,989, filed on Feb. 19, 2021, which is the National Stage filingunder 35 U.S.C. 371 of International Application No. PCT/KR2019/010750,filed on Aug. 23, 2019, which claims the benefit of earlier filing dateand right of priority to Korean Application No. 10-2018-0098876, filedon Aug. 23, 2018, the contents of which are all incorporated byreference herein their entirety.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The present disclosure relates to a scheme of transmitting/receivingdata in wireless communication, and more particularly, to a method andapparatus for transmitting/receiving information on a link forperforming communication in a wireless local area network (WLAN) system.

Related Art

A method for reducing power consumption in a wireless local area network(WLAN) has been improved in various manners. For example, in the IEEE802.11ah standard, a target wake time (TWT) technology has beenproposed. In addition, in the IEEE 802.11ax standard, the TWT technologyhas been extended to individual TWT or broadcast TWT technologies.

According to the broadcast TWT technology, a transmitting station (STA)(or an access point (AP)) may configure a service period (SP) in orderto transmit/receive buffered data to/from a receiving STA operating atlow power. The transmitting STA and the receiving STA may performcommunication within the SP. The transmitting STA may transmitinformation for configuring the SP to the receiving STA through abeacon.

SUMMARY

In general, a station (STA) based on the existing IEEE 802.11 standarduses one channel to transmit/receive one packet or frame. The existingSTA does not have to transmit a signal through a plurality of channels.A multi-link can be supported starting from the IEEE 802.11be standard.Therefore, when performing a target wake time (TWT) operation, theexisting STA cannot receive information for configuring a service period(SP) in a second link through a first link.

In addition, the receiving STA operating in a 6 GHz band does not have alegacy system, and thus may operate by prohibiting enhanced distributedchannel access (EDCA) to improve performance. Therefore, when operatingby prohibiting the EDCA, an operation of the receiving STA ortransmitting STA shall be compensated for.

An example according to the present specification proposes a method andapparatus for transmitting or receiving information on a link forperforming communication in a wireless local area network (WLAN) system.Specifically, there may be a need for a method in which information forcommunication to a second link is received through a first link andcommunication is performed through the second link.

A method performed in a WLAN system according to various embodiments mayinclude receiving, by a receiving STA supporting a multi-link includinga first link and a second link, a TWT element through the first link,wherein the TWT element is received through a beacon, and the TWTelement includes information for configuring a TWT period for the secondlink, configuring, by the receiving STA, the TWT period for the secondlink, based on the TWT element, and performing, by the receiving STA,communication with a transmitting STA through the second link within theTWT period.

Effects of the Disclosure

Based on an example according to the present specification, atransmission station (STA) (or an access point (AP)) may transmit abeacon to a receiving STA through a first link. The beacon may include atarget wake time (TWT) element. The TWT element may include informationfor configuring a service period (SP) through a second link. Therefore,the transmitting STA and the receiving STA may perform communicationwithin the SP through the second link. Specifically, the receiving STAmay transmit a trigger frame, and may perform communication, based on anOFDMA random access resource included in the trigger frame. Therefore,when a receiving STA operating at low power receives information of atransmission timing or the like of the trigger frame through the beacon,unnecessary power consumption may be reduced.

In addition, based on an example of the present specification, a methodof configuring an SP through a first link and performing communicationthrough a second link may enable effective signal transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual view illustrating a layered architecture of aWLAN system supported by IEEE 802.11.

FIG. 2 illustrates an example of a WLAN system.

FIG. 3 illustrates a frequency domain used in a WLAN system.

FIG. 4 illustrates an example regarding a network discovery/detection.

FIG. 5 illustrates an example of a PPDU transmitted/received by an STAof the present specification.

FIG. 6 illustrates an example of a PPDU according to the existing WLANstandard.

FIG. 7 illustrates another example of a PPDU according to the existingWLAN standard.

FIG. 8 illustrates another example of an HE-PPDU.

FIG. 9 illustrates a layout of resource units (RUs) used on a 20 MHzband.

FIG. 10 illustrates a layout of RUs used on a 40 MHz band.

FIG. 11 illustrates a layout of RUs used on an 80 MHz band.

FIG. 12 illustrates an example of UL MU communication.

FIG. 13 illustrates an example of a trigger frame.

FIG. 14 illustrates an example of a common information field.

FIG. 15 illustrates an example of a subfield included in a per-userinformation field.

FIG. 16 illustrates a method of performing UORA in a WLAN system.

FIG. 17 illustrates an example of a MAC frame.

FIG. 18 illustrates an example of a channel used/supported/definedwithin a 2.4 GHz band.

FIG. 19 illustrates an example of a channel used/supported/definedwithin a 5 GHz band.

FIG. 20 illustrates an example of a channel used/supported/definedwithin a 6 GHz band.

FIG. 21 illustrates an example of channel bonding.

FIG. 22 illustrates a technical feature of a link used in a multi-link.

FIG. 23 illustrates a first format of an EHT operation element.

FIG. 24 illustrates a second format of an EHT operation element.

FIG. 25 illustrates a third format of an EHT operation element.

FIG. 26 illustrates a fourth format of an EHT operation element.

FIG. 27 illustrates an example of a TWT procedure.

FIG. 28 to FIG. 30 illustrate a frame format of a TWT element.

FIG. 31 is a flowchart for describing an exemplary operation of atransmitting STA.

FIG. 32 is a flowchart for describing an exemplary operation of areceiving STA.

FIG. 33 illustrates a transmitting STA or a receiving STA to which anexample of the present disclosure is applied.

FIG. 34 illustrates another example of a detailed block diagram of atransceiver.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the present specification, when there is a description in which aconfiguration includes specific elements, or when there is a descriptionin which a process includes specific steps, it means that other elementsor other steps may be further included. That is, the terms used in thepresent specification are only for describing specific embodiments andare not intended to limit the concept of the present specification.

As used herein, a slash (/) or comma may indicate “and/or”. For example,“A/B” may indicate “A and/or B,” and therefore may mean “only A”, “onlyB”, or “A and B”. Technical features that are separately described inone drawing may be implemented separately or may be implementedsimultaneously.

As used herein, parentheses may indicate “for example”. Specifically,“control information (Signal)” may mean that “Signal” is proposed as anexample of “control information”. Further, “control information (i.e.,signal)” may also mean that “signal” is proposed as an example of“control information”.

The following examples of the present specification may be applied tovarious wireless communication systems. For example, the followingexamples of the present specification may be applied to a wireless localarea network (WLAN) system. For example, the present specification maybe applied to IEEE 802.11a/g/n/ac or IEEE 802.11ax. The presentspecification may also be applied to a newly proposed EHT standard or anew WLAN stand which has enhanced IEEE 802.11be.

Hereinafter, in order to describe a technical feature of the presentspecification, a technical feature of a WLAN system to which the presentspecification is applicable will be described.

FIG. 1 is a conceptual view illustrating a layered architecture of aWLAN system supported by IEEE 802.11. Referring to FIG. 1 , the layeredarchitecture of the WLAN system may include a physical medium dependent(PMD) sublayer 100, a physical layer convergence procedure (PLCP)sublayer 110, and a medium access control (MAC) sublayer 120.

The PLCP sublayer 100 may serve as a transmission interface fortransmitting/receiving data between a plurality of STAs. The PLCPsublayer 110 is implemented such that the MAC sublayer 120 is operatedwith a minimum dependency with respect to the PMD sublayer 100.

The PMD sublayer 100, the PLCP sublayer 110, and the MAC sublayer 120may conceptually include respective management entities. For example,the management entity of the MAC sublayer 120 is referred to as a MAClayer management entity (MLME) 125. The management entity of thephysical layer is referred to as a PHY layer management entity (PLME)115.

The management entities may provide an interface for performing a layermanagement operation. For example, the PLME 115 may be connected to theMLME 125 to perform a management operation of the PLCP sublayer 110 andthe PMD sublayer 100. The MLME 125 may be connected to the PLME 115 toperform a management operation of the MAC sublayer 120.

An STA management entity (SME) 150 may exist to perform a proper MAClayer operation. The SME 150 may be operated as a constitutional elementindependent of each layer. The PLME 115, the MLME 125, and the SME 150may mutually transmit and receive information on the basis of aprimitive.

The operation of each sublayer is briefly described as follows. Forexample, the PLCP sublayer 110 delivers a MAC protocol data unit (MPDU)received from the MAC sublayer 120 according to an instruction of theMAC layer between the MAC sublayer 120 and the PMD sublayer 100 to thePMD sublayer 100 or delivers a frame from the PMD sublayer 100 to theMAC sublayer 120.

The PMD sublayer 100 is a PLCP sublayer, and may transmit and receivedata between a plurality of STAs through a wireless medium. The MPDUdelivered from the MAC sublayer 120 is referred to as a physical servicedata unit (PSDU) in the PLCP sublayer 110. Although the MPDU is similarto the PSDU, if an aggregated MPDU (AMPDU) obtained by aggregating aplurality of MPDUs is delivered, the MPDUs may be individually differentfrom the PSDUs.

The PLCP sublayer 110 adds an additional field including informationrequired by a transceiver of a physical layer in a process of receivingthe PSDU from the MAC sublayer 120 and delivering it to the PMD sublayer100. In this case, the field added to the PSDU may be a PLCP preamble, aPLCP header, and tail bits required to return a convolution encoder to azero state.

The PLCP sublayer 110 adds the aforementioned fields to the PSDU togenerate a PLCP protocol data unit (PPDU) and transmits the PPDU to areceiving station through the PMD sublayer 100. The receiving stationreceives the PPDU to perform restoration by obtaining informationrequired to restore data from the PLCP preamble and the PLCP header.

The STA as any functional medium including a medium access control (MAC)that follows a regulation of the institute of electrical and electronicsengineers (IEEE) 802.11 standard and a physical layer interface for aradio medium may be used as a meaning including both AP and non-AP STAs.

The STA may be called in various names such as a mobile terminal, awireless device, a wireless transmit/receive unit (WTRU), a userequipment (UE), a mobile station (MS), a mobile subscriber unit, orsimply a user.

FIG. 2 illustrates an example of a WLAN system.

As illustrated, the WLAN system includes at least one access point (AP)and a plurality of STAs 520 a/b/c/e/d/f/g/h/i/j/k associated with theAP. The plurality of STAs in the example of FIG. 2 may perform an APand/or non-AP function. The plurality of STAs 520 a/b/c/e/d/f/g/h/i/j/kof FIG. 2 may be called in various terms such as a user terminal (UT),or the like. In addition, the at least one STA 520 f of FIG. 2 mayroute/relay communication between the plurality of APs 510 a/b, orcontrol the plurality of APs, or control the plurality of STA associatedwith the plurality of APs 510 a/b.

In addition, the AP 510 a/b of FIG. 2 may be associated with a systemcontrol device 530 to communicate with a different AP, or maycommunicate with another network entity (e.g., a network entity orInternet server defined by the 3GPP standard) other than the differentAP.

The plurality of STAs of FIG. 2 may configure a basic service set (BSS).

BSSs 100 and 105, as a set of an AP and an STA which are successfullysynchronized to communicate with each other, are not the conceptindicating a specific region. The BSS may include one or more STAs thatcan be coupled to one AP.

The BSS may include at least one STA, an AP providing a distributionservice, and a distribution system connecting a plurality of APs.

The distribution system may configure an extended service set (ESS) as aservice set extended by connecting several BSSs. The ESS may be used asa term indicating one network configured by connecting one or more APsthrough the distribution system. The AP included in one ESS may have thesame service set identification (SSID).

A portal may serve as a bridge which connects the WLAN network (IEEE802.11) and another network (e.g., 802.X).

The network may be configured even between the STAs without the AP toperform communication. Such a network may be called an Ad-Hoc network oran independent basic service set (IBSS).

FIG. 3 illustrates a frequency domain used in a WLAN system.

The WLAN system may use at least one channel defined within a 2.4 GHzband. The 2.4 GHz band may be called in other terms such as a first bandor the like.

As shown in FIG. 3 , 14 channels may be configured in a 2.4 GHz band.Each channel may be set to a frequency domain (or bandwidth) of 20 MHz.FO may indicate a center frequency. A center frequency of a channelwithin the 2.4 GHz band may be configured with an interval of about 5MHz, except for a channel 14. Among the 14 channels, adjacent channelsmay overlap with each other. For each county, an allowed frequencychannel or a maximum power level within the allowed frequency channelmay be set to be different. For example, a channel 13 may be a channelwhich is not allowed in North America but is allowed in most countries.

A specific numerical value shown in the example of FIG. 3 may bechanged.

FIG. 4 illustrates an example regarding a network discovery/detection.

An STA shall discover a network to access a WLAN network. Such adiscovery may be performed through a scanning process for the network.The scanning may be classified into active scanning and passivescanning.

As shown in FIG. 4 , an STA performing active scanning may transmit aprobe request frame and wait for a response thereof in order to searchfor a nearby AP while moving from one channel to another. A respondermay transmit a probe response frame to the STA which has transmitted theprobe request frame, in response to the probe request frame. Theresponder may be an STA which has last transmitted a beacon frame in aBSS of a channel being scanned. In the BSS, since an AP transmits thebeacon frame, the AP is the responder. In an IBSS, since STAs in theIBSS transmit the beacon frame in turn, the responder may be changed.

When the STA transmits the probe request frame through a channel 1 andreceives the probe response frame through the channel 1, the STA maystore BSS-related information included in the received probe responseframe, and may move to a next channel (e.g., a channel 2) to repeatscanning in the same manner.

As shown in FIG. 4 , the scanning operation may also be performed in apassive scanning manner. An STA performing scanning based on the passivescanning may receive a beacon frame while moving from one channel toanother.

The beacon frame is an example of a management frame in IEEE 802.11. Thebeacon frame may be periodically transmitted. An STA which has receivedthe beacon frame may store BSS-related information included in thereceived beacon frame and move to a next channel, and may performpassive scanning in the next channel.

Although not shown in FIG. 4 , a plurality of procedures may beperformed after the scanning procedure of FIG. 4 .

For example, an authentication process may be performed after thescanning procedure. The authentication process may include a process inwhich an STA transmits an authentication request frame to an AP, and theAP transmits an authentication response frame to the STA in responsethereto. An authentication frame used in the authenticationrequest/response corresponds to the management frame.

The authentication frames may include information about anauthentication algorithm number, an authentication transaction sequencenumber, a status code, a challenge text, a robust security network(RSN), and a finite cyclic group.

The STA may transmit the authentication request frame to the AP. The APmay determine whether to allow the authentication of the STA based onthe information included in the received authentication request frame.The AP may provide the authentication processing result to the STA viathe authentication response frame.

When the STA is successfully authenticated, the STA may perform anassociation process. The association process includes a process in whichthe STA transmits an association request frame to the AP and the APtransmits an association response frame to the STA in response. Theassociation request frame may include, for example, information aboutvarious capabilities, a beacon listen interval, a service set identifier(SSID), a supported rate, a supported channel, RSN, a mobility domain, asupported operating class, a traffic indication map (TIM) broadcastrequest, and an interworking service capability. The associationresponse frame may include, for example, information about variouscapabilities, a status code, an association ID (AID), a supported rate,an enhanced distributed channel access (EDCA) parameter set, a receivedchannel power indicator (RCPI), a received signal-to-noise indicator(RSNI), a mobility domain, a timeout interval (association comebacktime), an overlapping BSS scanning parameter, a TIM broadcast response,and a QoS map.

FIG. 5 illustrates an example of a PPDU transmitted/received by an STAof the present specification.

The example of FIG. 5 illustrates a representative field of the PPDU,and an order of fields shown in FIG. 5 may be variously changed.

The PPDU of FIG. 5 may include a short training field (STF) 510.

The STF 510 may be embodied as L-STF, HT-STF, VHT-STF, HE-STF, EHT-STF,or the like described below. The STF 510 may be used for framedetection, automatic gain control (AGC), diversity detection, and coarsefrequency/time synchronization.

The PPDU of FIG. 5 may include a long training field (LTF) 520.

The LTF 520 may be embodied as L-LTF, HT-LTF, VHT-LTF, HE-LTF, EHT-LTF,or the like described below. The LTF 520 may be used for finefrequency/time synchronization and channel prediction.

The PPDU of FIG. 5 may include an SIG 530.

The SIG 530 may be embodied as L-SIG, HT-SIG, VHT-SIG, HE-SIG, EHT-SIG,or the like described below. The SIG 530 may include control informationfor decoding the PPDU.

The PPDU of FIG. 5 may include a data field 540.

The data field 540 may include a service field 541, a physical layerservice data unit (PSDU) 542, a PPDU tail bit 543, and a padding bit544. Some bits of the service field 541 may be used for synchronizationof a descrambler at a receiving end. The PSDU 542 may correspond to aMAC protocol data unit (MPDU) defined in a MAC layer, and may includedata generated/used in an upper layer. The PPDU tail bit 543 may be usedto return an encoder to a zero state. The padding bit 544 may be used toadjust a length of the data field on a specific unit basis.

FIG. 6 illustrates an example of a PPDU according to the existing WLANstandard.

The PPDU shown in a sub-figure (a) of FIG. 6 is an example of the PPDUused in the IEEE 802.11a/g standard.

The PPDU shown in a sub-figure (b) of FIG. 6 is an example of the PPDUused in the IEEE 802.11n standard.

FIG. 7 illustrates another example of a PPDU according to the existingWLAN standard.

The example of FIG. 7 illustrates an example of the PPDU according tothe IEEE 802.11ac standard. The illustrated common fields include theexisting L-STF, L-LTF, and L-SIG, and also include a VHT-SIG-A fieldnewly proposed in the IEEE 802.11ac standard. The PPDU of FIG. 7 may beused both in single user (SU) communication in which a signal istransmitted from an AP to one user STA and multi-user (MU) communicationin which a signal is transmitted from the AP to a plurality of userSTAs. When the MU communication is performed, the VHT-SIG-A fieldincludes common control information commonly applied to all receivingSTAs.

When the MU communication is performed, per-user fields shown in FIG. 7include a field transmitted for at least any one user STA. The VHT-STFfield is an STF field newly proposed in the VHT standard (i.e., IEEE802.11ac), and the VHT-LTF field is an LTF field newly proposed in theVHT standard. The VHT-SIG-B field may include information for decoding adata field, and may be configured individually for each receiving STA.

The PPDU of FIG. 7 may be transmitted to a plurality of STAs, based on amulti-user multiple input multiple output (MU-MIMO) scheme. In addition,the PPDU may be transmitted to one STA, based on an SU-MIMO scheme.

FIG. 8 illustrates another example of an HE-PPDU.

The example of FIG. 8 may be applied to an IEEE 802.11ax or highefficiency (HE) WLAN system. Four types of PPDU formats are definedbased on IEEE 802.11ax, and the example of FIG. 8 is an example of anMU-PPDU used in MU communication. However, some of technical featuresapplied to the field shown in FIG. 8 may also be directly used in SUcommunication or UL-MU communication.

The technical feature of the HE-PPDU shown in FIG. 8 may also be appliedto an EHT-PPDU to be newly proposed. For example, the technical featureapplied to the HE-SIG may also be applied to the EHT-SIG, and thetechnical feature applied to the HE-STF/LTF may also be applied to theEHT-STF/LTF.

An L-STF of FIG. 8 may include a short training orthogonal frequencydivision multiplexing (OFDM) symbol. The L-STF may be used for framedetection, automatic gain control (AGC), diversity detection, and coarsefrequency/time synchronization.

An L-LTF of FIG. 8 may include a long training orthogonal frequencydivision multiplexing (OFDM) symbol. The L-LTF may be used for finefrequency/time synchronization and channel prediction.

An L-SIG of FIG. 8 may be used for transmitting control information. TheL-SIG may include information regarding a data rate and a data length.Further, the L-SIG may be repeatedly transmitted. That is, a new formatin which the L-SIG is repeated (for example, may be referred to asR-LSIG) may be configured.

An HE-SIG-A of FIG. 8 may include the control information common to areceiving STA.

Specifically, the HE-SIG-A may include information on: 1) a DL/ULindicator; 2) a BSS color field as an identifier of a BSS; 3) a fieldindicating a remaining time of a current TXOP period; 4) a bandwidthfield indicating whether it is 20, 40, 80, 160 and 80+80 MHz; 5) a fieldindicating an MCS scheme applied to the HE-SIG-B; 6) an indication fieldregarding whether the HE-SIG-B is modulated by a dual subcarriermodulation scheme for MCS; 7) a field indicating the number of symbolsused for the HE-SIG-B; 8) a field indicating whether the HE-SIG-B isgenerated across a full band; 9) a field indicating the number ofsymbols of the HE-LTF; 10) a field indicating the length of the HE-LTFand a CP length; 11) a field indicating whether an additional OFDMsymbol is present for LDPC coding; 12) a field indicating controlinformation regarding packet extension (PE); and 13) a field indicatinginformation on a CRC field of the HE-SIG-A. A specific field of theHE-SIG-A may be added or partially omitted. Further, some fields of theHE-SIG-A may be partially added or omitted in other environments otherthan a multi-user (MU) environment.

An HE-SIG-B of FIG. 8 may be included only in the case of the PPDU forthe multiple users (MUs) as described above. Basically, an HE-SIG-A oran HE-SIG-B may include resource allocation information (or virtualresource allocation information) for at least one receiving STA.

An HE-STF of FIG. 8 may be used for improving automatic gain controlestimation in a multiple input multiple output (MIMO) environment or anOFDMA environment.

An HE-LTF of FIG. 8 may be used for estimating a channel in the MIMOenvironment or the OFDMA environment.

The size of fast Fourier transform (FFT)/inverse fast Fourier transform(IFFT) applied to the HE-STF and the field after the HE-STF, and thesize of the FFT/IFFT applied to the field before the HE-STF may bedifferent from each other. For example, the size of the FFT/IFFT appliedto the HE-STF and the field after the HE-STF may be four times greaterthan the size of the FFT/IFFT applied to the field before the HE-STF.

For example, when at least one field of the L-STF, the L-LTF, the L-SIG,the HE-SIG-A, and the HE-SIG-B on the PPDU of FIG. 8 is referred to as afirst field/part, at least one of the data field, the HE-STF, and theHE-LTF may be referred to as a second field/part. The first field mayinclude a field associated with a legacy system, and the second fieldmay include a field associated with an HE system. In this case, the fastFourier transform (FFT) size and the inverse fast Fourier transform(IFFT) size may be defined as a size which is N (N is a natural number,e.g., N=1, 2, and 4) times greater than the FFT/IFFT size used in thelegacy WLAN system. That is, the FFT/IFFT size applied to the secondfield of the HE PPDU may be N(=4) times greater than that applied to thefirst field of the HE PPDU. For example, 256FFT/IFFT may be applied to abandwidth of 20 MHz, 512FFT/IFFT may be applied to a bandwidth of 40MHz, 1024FFT/IFFT may be applied to a bandwidth of 80 MHz, and2048FFT/IFFT may be applied to a bandwidth of continuous 160 MHz ordiscontinuous 160 MHz.

In other words, a subcarrier space/spacing may have a size which is 1/Ntimes (N is the natural number, e.g., N=4, the subcarrier spacing is setto 78.125 kHz) the subcarrier space used in the legacy WLAN system. Thatis, a subcarrier spacing having a size of 312.5 kHz, which is a legacysubcarrier spacing, may be applied to the first field/part of the HEPPDU and a subcarrier space having a size of 78.125 kHz may be appliedto the second field/part of the HE PPDU.

Alternatively, it may be expressed that an IDFT/DFT period applied toeach symbol of the first field is N(=4) times shorter than the IDFT/DFTperiod applied to each data symbol of the second field. That is, it maybe expressed that the IDFT/DFT length applied to each symbol of thefirst field of the HE PPDU is 3.2 μs and the IDFT/DFT length applied toeach symbol of the second field of the HE PPDU is 3.2 μs*4 (=12.8 μs).The length of the OFDM symbol may be a value obtained by adding thelength of a guard interval (GI) to the IDFT/DFT length. The length ofthe GI may have various values such as 0.4 μs, 0.8 μs, 1.6 μs, 2.4 μs,and 3.2 μs.

The technical feature in which subcarrier spacings having differentsizes are applied to one PPDU may also be applied directly to theEHT-PPDU. That is, a subcarrier spacing of 312.5 kHz may be applied to afirst portion/part of the EHT-PPDU, and a subcarrier spacing of 78.125kHz may be applied to a second field/part of the EHT-PPDU. The firstportion/part of the EHT-PPDU may include L-LTF, L-STF, L-SIG, EHT-SIG-A,and/or EHT-SIG-B. In addition, a second portion/part of the EHT-PPDU mayinclude EHT-STF, EHT-LTF, and/or a data field. The division of the firstportion/second portion of the EHT-PPDU may be changed

Hereinafter, a resource unit (RU) used in the PPDU is described. The RUmay include a plurality of subcarriers (or tones). The RU may be usedwhen a signal is transmitted to a plurality of STAs, based on an OFDMAscheme. In addition, the RU may also be defined when a signal istransmitted to one STA. The RU may be used for the STF, the LTF, thedata field, or the like.

FIG. 9 illustrates a layout of resource units (RUs) used on a 20 MHzband.

As illustrated in FIG. 9 , RUs corresponding to tones (i.e.,subcarriers) different in number may be used to configure some fields ofthe HE-PPDU. For example, the resources may be allocated by the unit ofRUs illustrated for the HE-STF, the HE-LTF, and the data field.

As illustrated in an uppermost part of FIG. 9 , a 26-unit (i.e., a unitcorresponding to 26 tones) may be disposed. 6 tones may be used as aguard band in a leftmost band of the 20 MHz band, and 5 tones may beused as a guard band in a rightmost band of the 20 MHz band. Further, 7DC tones may be inserted into a center band, that is, a DC band, and a26-unit corresponding each 13 tones may be present at left and rightsides of the DC band. Further, the 26-unit, a 52-unit, and a 106-unitmay be allocated to other bands. Each unit may be allocated for areceiving STA, that is, a user.

Meanwhile, the RU layout of FIG. 9 may be used not only in a multi-user(MU) situation but also in a single user (SU) situation. In this case,as illustrated in a lowermost part of FIG. 9 , it is possible to use one242-unit, and 3 DC tones may be inserted.

In an example of FIG. 9 , RUs having various sizes, that is, a 26-RU, a52-RU, a 106-RU, a 242-RU, and the like are proposed. As a result, sincespecific sizes of the RUs may be extended or increased, the presentembodiment is not limited to a specific size (i.e., the number ofcorresponding tones) of each RU.

FIG. 10 illustrates a layout of RUs used on a 40 MHz band.

Similarly to a case in which the RUs having various sizes are used inthe example of FIG. 9 , a 26-RU, a 52-RU, a 106-RU, a 242-RU, a 484-RU,and the like may also be used in an example of FIG. 10 . Further, 5 DCtones may be inserted into a center frequency, 12 tones may be used as aguard band in a leftmost band of a 40 MHz band, and 11 tones may be usedas a guard band in a rightmost band of the 40 MHz band.

In addition, as illustrated, when used for a single user, the 484-RU maybe used. Meanwhile, the specific number of RUs may be changed similarlyto the example of FIG. 9 .

FIG. 11 illustrates a layout of RUs used on an 80 MHz band.

Similarly to a case in which the RUs having various sizes are used inthe examples of FIG. 9 and FIG. 10 , a 26-RU, a 52-RU, a 106-RU, a242-RU, a 484-RU, and the like may also be used in an example of FIG. 11. Further, 7 DC tones may be inserted into a center frequency, 12 tonesmay be used as a guard band in a leftmost band of an 80 MHz band, and 11tones may be used as a guard band in a rightmost band of the 80 MHzband. Furthermore, the 26-RU, which uses each 13 tones located at leftand right sides of the DC band, may be used.

In addition, as illustrated, when used for a single user, the 996-RU maybe used. In this case, 5 DC tones may be inserted.

Meanwhile, the specific number of RUs may be changed similarly to theexample of FIG. 9 and FIG. 10 .

The RU shown in FIG. 9 to FIG. 11 may be used in OFDMA-basedcommunication. That is, any one RU(26/52/106/242-RU, etc.) shown in FIG.9 to FIG. 11 may be allocated to any one STA, and another RU may beallocated to another STA. That is, MU communication is possible in sucha manner that the RU shown in FIG. 9 to FIG. 11 is allocated to aplurality of STAs. The MU communication may be applied to downlinkcommunication and may also be applied to uplink communication.

The MU PPDU shown in FIG. 8 may be used for DL MU communication. Thatis, the DL-MU communication is possible through an OFDMA and/or MU-MIMOscheme, based on the PPDU of FIG. 8 .

In addition, UL MU communication is also supported in the WLAN system. Atrigger frame is defined for UL MU communication. The trigger frame mayinclude ID information for a plurality of STAs participating in UL MUcommunication and a radio resource (e.g., RU information) used in the ULMU communication.

FIG. 12 illustrates an example of UL MU communication.

According to the example of FIG. 12 , an AP transmits a trigger frame1330. The trigger frame may be defined in the form of a MAC frame, andmay be transmitted from the AP by being included in a PPDU of variousformats. That is, when the PPDU including the trigger frame 1330 isreceived in an STA, UL MU communication starts after a short interframespace (SIFS) period. Specifically, a plurality of STAs (i.e., an STA 1to an STA n) indicated by the trigger frame 1330 perform the UL-MUcommunication, based on an uplink resource (i.e., RU) indicated by thetrigger frame 1330. Specifically, the plurality of STAs (i.e., the STA 1to the STA n) transmit to the AP a trigger based (TB) PPDU according tothe IEEE 802.11ax standard. A plurality of TB PPDUs transmitted by theplurality of STAs may be transmitted in the same time period, andinformation on the same time period may be included in the trigger frame1330. Thereafter, the AP may transmit an ACK/NACK signal for TB PPDUs1341 and 1342 through a block ACK (BA). The UL MU communication may beperformed within a period of a TXOP 1325 obtained by the AP.

FIG. 13 illustrates an example of a trigger frame. The trigger frame ofFIG. 13 may allocate a resource for uplink multiple-user (MU)transmission, and may be transmitted from an AP. The trigger frame mayconsist of a MAC frame, and may be included in a PPDU.

Some of fields shown in FIG. 13 may be omitted, and another field may beadded. In addition, a length of each field may be changed to bedifferent from that shown in the drawing.

A frame control field 1310 of FIG. 13 may include information on aversion of a MAC protocol and extra other control information, and aduration field 1320 may include time information for configuring anetwork allocation vector (NAV) described below or information on a UEidentifier (e.g., AID).

In addition, an RA field 1330 includes address information of areceiving STA of a corresponding trigger frame, and may be optionallyomitted. A TA field 1340 includes address information of an STA (e.g.,AP) transmitting a corresponding trigger frame, and a common informationfield 1350 includes common control information applied to the receivingSTA which receives a corresponding trigger frame.

FIG. 14 illustrates an example of a common information field. Some ofsubfields of FIG. 14 may be omitted, and extra subfields may be added.In addition, a length of each of the illustrated subfields may bechanged.

A length field 1410 illustrated herein has the same value as a lengthfield of an L-SIG field of an uplink PPDU transmitted in response to acorresponding trigger frame, and the length field of the L-SIG field ofthe uplink PPDU indicates a length of the uplink PPDU. As a result, thelength field 1410 of the trigger frame may be used to indicate a lengthof a corresponding uplink PPDU.

In addition, a cascade indicator field 1420 indicates whether a cascadeoperation is performed. The cascade operation implies that downlink MUtransmission and uplink MU transmission are performed together withinthe same TXOP. That is, it implies that the uplink MU transmission isperformed when a pre-set time (e.g., SIFS) elapses, after the downlinkMU transmission is performed. During the cascade operation, there may beonly one transmitting device (e.g., AP) performing downlinkcommunication, and there may be a plurality of transmitting devices(e.g., non-AP) performing uplink communication.

A CS request field 1430 indicates whether it is necessary to consider aradio medium state or an NAV or the like in a situation where areceiving device which has received a corresponding trigger frametransmits an uplink PPDU.

An HE-SIG-A information field 1440 may include information forcontrolling content of an SIG-A field (i.e., HE-SIG-A field) of anuplink PPDU transmitted in response to a corresponding trigger frame.

A CP and LTF type field 1450 may include information on a CP length andLTF length of an uplink PPDU transmitted in response to a correspondingtrigger frame. A trigger type field 1460 may indicate a purpose of usingthe corresponding trigger frame, for example, typical triggering,triggering for beamforming, a request for block ACK/NACK, or the like.

Meanwhile, the remaining descriptions on FIG. 13 are added as follows.

Per-user information fields 1360 #1 to 1360 #N corresponding to thenumber of receiving STAs receiving the trigger frame of FIG. 13 arepreferably included. The per-user information field may also be calledan “RU allocation field”.

In addition, the trigger frame of FIG. 13 may include a padding field1370 and a frame check sequence field 1380.

Each of the per-user information fields 1360 #1 to 1360 #N shown in FIG.13 preferably includes a plurality of subfields.

FIG. 15 illustrates an example of a subfield included in a per-userinformation field. Some of the subfields of FIG. 15 may be omitted, andextra subfields may be added. In addition, a length of each of theillustrated subfields may be changed.

A user identifier field 1510 of FIG. 15 indicates an identifier of anSTA (e.g., a receiving STA) corresponding to per-user information. Anexample of the identifier may be the entirety or part of an AID.

In addition, an RU allocation field 1520 may be included. That is, whenthe receiving STA which is identified by using the user identifier field1510 transmits an uplink PPDU in response to the trigger frame of FIG. 9, the uplink PPDU is transmitted through an RU indicated by the RUallocation field 1520. In this case, the RU indicated by the RUallocation field 1520 preferably indicates the RU shown in FIG. 9 , FIG.10 , and FIG. 11 .

The subfield of FIG. 15 may include a coding type field 1530. The codingtype field 1530 may indicate a coding type of an uplink PPDU transmittedin response to the trigger frame of FIG. 13 . For example, when BCCcoding is applied to the uplink PPDU, the coding type field 1530 may beset to ‘1’, and when LDPC coding is applied, the coding type field 1530may be set to ‘0’.

In addition, the subfield of FIG. 15 may include an MCS field 1540. TheMCS field 1540 may indicate an MCS scheme applied to the uplink PPDUtransmitted in response to the trigger frame of FIG. 13 .

Meanwhile, an STA may transmit various feedback schedules (e.g., bufferstatus report, channel state information, or the like) based on UL OFDMArandom access (UORA) defined according to the IEEE 802.11ax standard.

FIG. 16 illustrates a method of performing UORA in a WLAN system.

As illustrated, an AP may allocate 6 RU resources as shown in FIG. 16through a trigger frame (e.g., the trigger frame of FIG. 13 to FIG. 15). Specifically, the AP may allocate a 1^(st) RU resource (AID 0, RU 1),a 2^(nd) RU resource (AID 0, RU 2), a 3^(rd) RU resource (AID 0, RU 3),a 4^(th) RU resource (AID 2045, RU 4), a 5^(th) RU resource (AID 2045,RU 5), and a 6^(th) RU resource (AID 2045, RU 6). Information on the AID0 or AID 2045 may be included, for example, in the user identifier field1110 of FIG. 11 . Information on the RU 1 to RU 6 may be included, forexample, in the RU allocation field 1120 of FIG. 11 . AID=0 may imply aUORA resource for an associated STA, and AID=2045 may imply a UORAresource for an un-associated STA. Accordingly, the 1^(st) to 3^(rd) RUresources of FIG. 16 may be used as a UORA resource for the associatedSTA, the 4^(th) and 5^(th)RU resources may be used as a UORA resourcefor the un-associated STA, and the 6^(th) RU resource of FIG. 16 may beused as a typical resource for UL MU.

In the example of FIG. 16 , an OFDMA random access backoff (OBO) of anSTA1 is decreased to 0, and the STA1 randomly selects the 2^(nd) RUresource (AID 0, RU 2). In addition, since an OBO counter of an STA2/3is greater than 0, an uplink resource is not allocated to the STA2/3. Inaddition, regarding an STA4 in FIG. 16 , since an AID (e.g., AID=3) ofthe STA4 is included in a trigger frame, a resource of the RU 6 isallocated without backoff.

Specifically, since the STA1 of FIG. 16 is an associated STA, the totalnumber of eligible RA RUs for the STA1 is 3 (RU 1, RU 2, and RU 3), andthus the STA1 decreases an OBO counter by 3 so that the OBO counterbecomes 0. In addition, since the STA2 of FIG. 16 is an associated STA,the total number of eligible RA RUs for the STA2 is 3 (RU 1, RU 2, andRU 3), and thus the STA2 decreases the OBO counter by 3 but the OBOcounter is greater than 0. In addition, since the STA3 of FIG. 16 is anun-associated STA, the total number of eligible RA RUs for the STA3 is 2(RU 4, RU 5), and thus the STA3 decreases the OBO counter by 2 but theOBO counter is greater than 0.

FIG. 17 illustrates an example of a MAC frame.

The MAC frame of FIG. 17 may be included in a PSDU included in a datafield of a PPDU. A length of each of fields shown in FIG. 17 may bechanged, and some of the fields may be omitted. As illustrated, the MACframe may include a MAC header.

The data field may include a service field, a physical layer servicedata unit (PSDU), and a PPDU tail bit, and may also optionally include apadding bit. Some bits of the service field may be used forsynchronization of a descrambler at a receiving end. The PSDU maycorrespond to a MAC protocol data unit (MPDU) defined in a MAC layer,and may include data generated/used in an upper layer. The PPDU tail bitmay be used to return an encoder to a zero state. The padding bit may beused to adjust a length of the data field on a specific unit basis.

The MPDU is defined according to various MAC frame formats, and a basicMAC frame consists of a MAC header, a frame body, and a frame checksequence (FCS). The MAC frame may consist of the MPDU and may betransmitted/received through a PSDU of a data part of the PPDU frameformat.

The MAC header includes a frame control field, a duration/ID field, anaddress field, or the like. The frame control field may include aplurality of pieces of control information required for frametransmission/reception. The duration/ID field may be set to a time fortransmitting a corresponding frame or the like.

The duration/ID field included in the MAC header may be set to a 16-bitlength (e.g., B0 to B15). Content included in the duration/ID field mayvary depending on a frame type and sub-type, whether it is transmittedduring a contention free period (CFP), QoS capability of a transmittingSTA, or the like. (i) In a control frame of which a sub-type is PS-Poll,the duration/ID field may include an AID of a transmitting STA (e.g.,through 14 LSB bits), and 2 MSB bits may be set to 1. (ii) In frames tobe transmitted during CFP by a point coordinator (PC) or a non-QoS STA,the duration/ID field may be set to a fixed value (e.g., 32768). (iii)In other frames transmitted by the non-QoS STA or control framestransmitted by the QoS STA, the duration/ID field may include a durationvalue defined for each frame type. In a data frame or management frametransmitted by the QoS STA, the duration/ID field may include a durationvalue defined for each frame type. For example, when it is set to B15=0in the duration/ID field, it may indicate that the duration/ID field isused to indicate a TXOP duration, and B0 to B14 may be used to indicatea real TXOP duration in practice. The real TXOP duration indicated bythe B0 to B14 may be any one of values 0 to 32767, and a unit thereofmay be microseconds (us). However, when the duration/ID field indicatesa fixed TXOP duration value (e.g., 32768), it may be set to B15=1 andB0˜B14=0. In addition, when it is set to B14=1 and B15=1, theduration/ID field is used to indicate an AID, and B0 to B13 indicate oneof AIDs 1 to 2007.

The frame control field of the MAC header may include Protocol Version,Type, Subtype, To DS, From DS, More Fragment, Retry, Power Management,More Data, Protected Frame, and Order subfields.

The STA (AP and/or non-AP STA) of the present specification may supportmulti-link communication. The STA supporting multi-link communicationmay perform communication simultaneously through a plurality of links.That is, the STA supporting multi-link communication may performcommunication through the plurality of links during a first time period,and may perform communication through only any one of the plurality oflinks during a second time period.

The multi-link communication may imply communication supporting theplurality of links, and the link may include one channel (e.g.,20/40/80/160/240/320 MHz channel) defined in a 2.4 GHz band, a 5 GHzband, a 6 GHz band, and a specific band defined in a specific band.Hereinafter, various bands and channels will be described.

FIG. 18 illustrates an example of a channel used/supported/definedwithin a 2.4 GHz band.

The 2.4 GHz band may be called in other terms such as a first band. Inaddition, the 2.4 GHz band may imply a frequency domain in whichchannels of which a center frequency is close to 2.4 GHz (e.g., channelsof which a center frequency is located within 2.4 to 2.5 GHz) areused/supported/defined.

A plurality of 20 MHz channels may be included in the 2.4 GHz band. 20MHz within the 2.4 GHz may have a plurality of channel indices (e.g., anindex 1 to an index 14). For example, a center frequency of a 20 MHzchannel to which a channel index 1 is allocated may be 2.412 GHz, acenter frequency of a 20 MHz channel to which a channel index 2 isallocated may be 2.417 GHz, and a center frequency of a 20 MHz channelto which a channel index N is allocated may be (2.407+0.005*N)GHz. Thechannel index may be called in various terms such as a channel number orthe like. Specific numerical values of the channel index and centerfrequency may be changed.

FIG. 18 exemplifies 4 channels within a 2.4 GHz band. Each of 1^(st) to4^(th) frequency domains 1810 to 1840 shown herein may include onechannel. For example, the 1^(st) frequency domain 1810 may include achannel 1 (a 20 MHz channel having an index 1). In this case, a centerfrequency of the channel 1 may be set to 2412 MHz. The 2^(nd) frequencydomain 1820 may include a channel 6. In this case, a center frequency ofthe channel 6 may be set to 2437 MHz. The 3^(rd) frequency domain 1830may include a channel 11. In this case, a center frequency of thechannel 11 may be set to 2462 MHz. The 4^(th) frequency domain 1840 mayinclude a channel 14. In this case, a center frequency of the channel 14may be set to 2484 MHz.

FIG. 19 illustrates an example of a channel used/supported/definedwithin a 5 GHz band.

The 5 GHz band may be called in other terms such as a second band or thelike. The 5 GHz band may imply a frequency domain in which channels ofwhich a center frequency is greater than or equal to 5 GHz and less than6 GHz (or less than 5.9 GHz) are used/supported/defined. Alternatively,the 5 GHz band may include a plurality of channels between 4.5 GHz and5.5 GHz. A specific numerical value shown in FIG. 19 may be changed.

A plurality of channels within the 5 GHz band include an unlicensednational information infrastructure (UNII)-1, a UNII-2, a UNII-3, and anISM. The INII-1 may be called UNII Low. The UNII-2 may include afrequency domain called UNII Mid and UNII-2 Extended. The UNII-3 may becalled UNII-Upper.

A plurality of channels may be configured within the 5 GHz band, and abandwidth of each channel may be variously set to, for example, 20 MHz,40 MHz, 80 MHz, 160 MHz, or the like. For example, 5170 MHz to 5330 MHzfrequency domains/ranges within the UNII-1 and UNII-2 may be dividedinto eight 20 MHz channels. The 5170 MHz to 5330 MHz frequencydomains/ranges may be divided into four channels through a 40 MHzfrequency domain. The 5170 MHz to 5330 MHz frequency domains/ranges maybe divided into two channels through an 80 MHz frequency domain.Alternatively, the 5170 MHz to 5330 MHz frequency domains/ranges may bedivided into one channel through a 160 MHz frequency domain.

FIG. 20 illustrates an example of a channel used/supported/definedwithin a 6 GHz band.

The 6 GHz band may be called in other terms such as a third band or thelike. The 6 GHz band may imply a frequency domain in which channels ofwhich a center frequency is greater than or equal to 5.9 GHz areused/supported/defined. A specific numerical value shown in FIG. 20 maybe changed.

For example, the 20 MHz channel of FIG. 20 may be defined starting from5.940 GHz. Specifically, among 20 MHz channels of FIG. 20 , a leftmostchannel may have an index 1 (or a channel index, a channel number,etc.), and 5.945 GHz may be assigned as a center frequency. That is, acenter frequency of a channel of an index N may be determined as(5.940+0.005*N)GHz.

Accordingly, an index (or channel number) of the 2 MHz channel of FIG.20 may be 1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61,65, 69, 73, 77, 81, 85, 89, 93, 97, 101, 105, 109, 113, 117, 121, 125,129, 133, 137, 141, 145, 149, 153, 157, 161, 165, 169, 173, 177, 181,185, 189, 193, 197, 201, 205, 209, 213, 217, 221, 225, 229, 233. Inaddition, according to the aforementioned (5.940+0.005*N)GHz rule, anindex of the 40 MHz channel of FIG. 20 may be 3, 11, 19, 27, 35, 43, 51,59, 67, 75, 83, 91, 99, 107, 115, 123, 131, 139, 147, 155, 163, 171,179, 187, 195, 203, 211, 219, 227.

Although 20, 40, 80, and 160 MHz channels are illustrated in the exampleof FIG. 20 , a 240 MHz channel or a 320 MHz channel may be additionallyadded.

Hereinafter, the concept of channel bonding will be described.

For example, in an IEEE 802.11n system, 40 MHz channel bonding may beperformed by coupling two 20 MHz channels. In addition, in an IEEE802.11ac system, 40/80/160 MHz channel bonding may be performed.

For example, an STA may perform channel bonding for a primary 20 MHzchannel (P20 channel) and a secondary 20 MHz channel (S20 channel). Abackoff count/counter may be used in a channel bonding process. Abackoff count value may be selected as a random value, and may bedecreased during a backoff interval. In general, when the backoff countvalue is 0, the STA may attempt an access to a channel.

The STA which performs channel bonding determines whether the S20channel has maintained an idle state during a specific period (e.g.,point coordination function interframe space (PIFS)), at a timing atwhich a backoff count value for the P20 channel is 0 since it isdetermined that the P20 channel is in the idle state during the backoffinterval. If the S20 channel is in the idle state, the STA may performbonding for the P20 channel and the S20 channel. That is, the STA maytransmit a signal (PPDU) through the 40 MHz channel (i.e., 40 MHzbonding channel) including the P20 channel and the S20 channel.

FIG. 21 illustrates an example of channel bonding. As shown in FIG. 21 ,a primary 20 MHz channel and a secondary 20 MHz channel may configure a40 MHz channel (primary 40 MHz channel) through channel bonding. Thatis, the bonded 40 MHz channel may include the primary 20 MHz channel andthe secondary 20 MHz channel.

The channel bonding may be performed when a channel consecutive to theprimary channel is in an idle state. That is, the primary 20 MHzchannel, the secondary 20 MHz channel, a secondary 40 MHz channel, and asecondary 80 MHz channel may be bonded sequentially. If it is determinedthat the secondary 20 MHz channel is in a busy state, the channelbonding may not be performed even if all other secondary channels are inthe idle state. In addition, if it is determined that the secondary 20MHz channel is in the idle state and the secondary 40 MHz channel is inthe busy state, the channel bonding may be performed only for theprimary 20 MHz channel and the secondary 20 MHz channel.

Hereinafter, a technical feature for multi-link and aggregation will bedescribed.

An STA (AP and/or non-AP STA) of the present specification may supportmulti-link communication. That is, the STA may transmit/receive a signalsimultaneously through a first link and a second link, based on themulti-link. That is, the multi-link may imply a scheme in which one STAtransmits/receives a signal simultaneously through a plurality of links.For example, transmitting of a signal through any one link and receivingof a signal through another link may also be included in multi-linkcommunication. An STA supporting a multi-link may use a plurality oflinks in a first time period, and may use only one link in a second timeperiod.

FIG. 22 illustrates a technical feature of a link used in a multi-link.

A link used in a multi-link may have at least one of technical featuresas follows. A feature regarding a link described below is for exemplarypurposes, and an additional technical feature is also applicable.

For example, respective links used in the multi-link may be included indifferent bands. That is, when the multi-link in use supports first andsecond links, each of the first and second links is included within a2.4 GHz band, a 5 GHz band, or a 6 GHz band, but the first link and thesecond link may be included in different bands.

Referring to FIG. 22 , a first link 2210 and a second link 220 may beused for the multi-link. The first link 2210 of FIG. 22 may be included,for example, in the 5 GHz band. The second link 2220 of FIG. 22 may beincluded, for example, in the 6 GHz band.

Each of the links included in the multi-link may also be included in thesame band. For example, when the multi-link in use supports thefirst/second/third links, all of the links may be included in the sameband, or the first/second links may be included in a first band and thethird link may be included in a second band.

The multi-link may be configured based on different RF modules (e.g., atransmitting/receiving device including an IDFT/IFFT/DFT/FFT block and abaseband processing device). Additionally or alternatively, a pluralityof links included in the multi-link may be discontinuous in a frequencydomain. That is, among the plurality of links, a frequency gap may existin a frequency domain corresponding to the first link and a frequencydomain corresponding to the second link.

As shown in FIG. 22 , the first link 2210 may include a plurality ofchannels 2211, 2212, 2213, and 2214. An STA may apply the existingchannel bonding to the plurality of channels 2211, 2212, 2213, and 2214.That is, when the plurality of channels 2211, 2212, 2213, and 2214 arein an idle state during a specific time period (e.g., during a PIFS),the plurality of channels 2211, 2212, 2213, and 2214 may consist of asingle bonding channel, and the single bonding channel may operatethrough the single link 2210. Alternatively, some channels (e.g., 2211,2212, and 2214) among the plurality of channels 2211, 2212, 2213, and2214 may operate through the single link 2210 according to a preamblepuncturing scheme newly proposed in the IEEE 802.11ax standard. Theaforementioned feature may be equally applied to the second link 2220.

The number (and/or a maximum bandwidth) of channels included in a singlelink used in the multi-link may have an upper limit. For example, up tofour channels may configure the single link as in the example of FIG. 22. Additionally or alternatively, a maximum bandwidth of the single linkmay be 160 MHz, 240 MHz, or 320 MHz. Additionally or alternatively, thesingle link may include only continuous channels. A specific numericalvalue mentioned above may be changed.

A procedure of identifying/specifying/determining a link used in themulti-link relates to an aggregation (or channel aggregation) procedure.The STA may aggregate a plurality of links to perform multi-linkcommunication. That is, the STA may perform: 1) a first procedure ofidentifying/specifying/determining links aggregated for the multi-link;and 2) a second procedure of performing multi-link communication throughthe identified/specified/determined links. The STA may perform the firstand second procedures as a separate procedure, or may perform theprocedures simultaneously as a single procedure.

Hereinafter, a technical feature for the first procedure will bedescribed.

An STA may transmit/receive information on a plurality of linksconstituting a multi-link. For example, through a beacon, a proberesponse, an association response, or an extra control frame, an AP maytransmit identification information regarding a band in which capabilityof the multi-link is supported and/or identification informationregarding a channel in which capability of the multi-link is supported.For example, when the AP can perform communication by aggregating somechannels within a 5 GHz band and some channels within a 6 GHz band,identification information regarding channels that can be aggregated maybe transferred to a user STA.

For example, through a probe request, an association response, or anextra control frame, the user STA may also transmit identificationinformation regarding a band in which capability of the multi-link issupported and/or identification information regarding a channel in whichcapability of the multi-link is supported. For example, when the userSTA can perform communication by aggregating some channels within a 5GHz band and some channels within a 6 GHz band, identificationinformation regarding channels that can be aggregated may be transferredto the AP.

Any one of the plurality of links constituting the multi-link mayoperate as a primary link. The primary link may perform variousfunctions. For example, when a backoff value of the primary link is 0(and/or the primary link is idle during a PIFS), an STA may aggregateother links. Information regarding the primary link may also be includedin the beacon, the probe request/response, and the associationrequest/response.

The user-STA/AP may specify/determine/obtain a band and/or channel inwhich the multi-link is performed through a negotiation procedure ofexchanging information regarding capability thereof.

For example, through the negotiation procedure, the STA mayspecify/determine/obtain a first candidate band/channel that can be usedfor a first link, a second candidate band/channel that can be used for asecond link, and a third candidate band/channel that can be used for athird link.

Thereafter, the STA may perform the procedure ofidentifying/specifying/determining links aggregated for the multi-link.For example, the STA may aggregate at least two bands/channels, based ona backoff count of the first candidate band/channel, second candidateband/channel, and third candidate band/channel and/or a clear channelassessment (CCA) sensing result (whether it is busy/idle). For example,the STA may aggregate the second candidate band/channel which hasmaintained an idle state during a specific period (during a PIFS), at atiming at which the backoff count value of the first candidateband/channel is 0. That is, the STA may determine/specify the firstcandidate band/channel as the first link for the multi-link, maydetermine/specify the second candidate band/channel as the second linkfor the multi-link, and may perform multi-link communication through thefirst and second links.

Hereinafter, a technical feature for the second procedure will bedescribed.

For example, when an STA determines to aggregate the first and secondlinks, the STA may perform multi-link communication through the firstand second links. For example, the STA may transmit a PPDU of the samelength through all of the first and second links. Alternatively, the STAmay receive a transmission PPDU through the first link, and may receivea reception PPDU through the second link during an overlapping timeperiod. The STA may perform communication through all aggregated linksin a specific time period, and may use only any one link in another timeperiod.

An STA (user-STA/AP) of the present specification may include aplurality of RF modules/units. For example, when the STA transmits asignal of a 2.4 GHz band by using the RF module/unit for a 5 GHz and/or6 GHz band, performance deterioration may occur in the STA. Therefore,the STA may additionally include the RF module/unit for the 2.4 GHzband, distinct from the RF module/unit for the 5 GHz and/or 6 GHz band.

As described above, the STA of the present specification can operate invarious bands/channels. Accordingly, an operation of transferringaccurate information regarding a band and/or channel shall be definedfor the user-STA/AP.

For this, the present specification proposes a plurality of embodiments.

At least one (e.g., a first embodiment) of the following examplesproposes an example in which an AP informs an STA of a multi-bandchannel or an ultra-wideband channel greater than or equal to 160 MHz.Specifically, the present specification proposes an EHT operationelement transmitted through a beacon frame, a probe response frame, oran association response frame. The EHT operation element proposed in thepresent specification may be a format based on the IEEE 802.11bestandard. The EHT operation element may support a technical featuredescribed below.

Since the at least one (e.g., the first embodiment) of the followingexamples is related to an example for informing of a multi-band channelor an ultra-wideband channel greater than or equal to 160 MHz, thefollowing technical feature is not limited to the term EHT. That is, theterm EHT may be changed/omitted, and the EHT operation element may becalled in various terms such as a new type operation element, a firsttype operation element, or the like. For example, the followingtechnical feature may be applied to the EHT standard or a new WLANstandard enhanced from IEEE 802.11be.

First Embodiment

Hereinafter, for convenience of explanation, a related technical featurewill be described based on an EHT operation element.

An AP (or a transmitting STA) may define information on an operatingchannel with respect to a specific element. That is, the element mayinclude information on a channel in which the AP operates. The elementmay be transmitted to an STA by being included in a beacon frametransmitted periodically from the AP. The STA may identify theinformation on the operating channel of the AP by receiving the beaconframe. In addition, when the STA requests the AP to providechannel-related information or connection in a state where the elementis included in a probe response frame or an association response frameor the like, the element may be transmitted to the STA in response tothe request.

In the IEEE 802.11n standard, 40 MHz channel information may be definedthrough the HT operation element. In addition, in the IEEE 802.11ac,information on an 80 MHz or 160 MHz channel may be defined through theVHT operation element. Since wideband channel transmission is notexplicitly specified in the IEEE 802.11ax standard, the HE operationelement may not include information on the existing band/channel.However, since the IEEE 802.11ax supports a 6 GHz band operation, the HEoperation element may include information on a channel in a 6 GHz band,instead of the information on the existing band channel. An STA (e.g.,EHT-STA) supporting a subsequent standard (e.g., IEEE 803.11be) afterIEEE 802.11ax may support an ultra-wideband channel greater than orequal to 160 MHz. In addition, the EHT-STA may transmit a signal througha channel within a plurality of bands (e.g., 2.4 GHz or 5 GHz) or maytransmit a signal through a plurality of links. For example, one BSS mayuse an up to 200 MHz channel by using a 40 MHz channel in a 2.4 GHz bandand a 160 MHz channel in a 5 GHz band together.

An AP and/or STA according to the present specification may include 4 RFunits, and may operate in 3 bands of 2.4 GHz, 5 GHz, and 6 GHz. Thenumber of RF units or the number of supported bands may be changed.According to an embodiment, the AP and/or the STA may include 4 or moreRF units. The AP and/or STA of the present specification may operate inat least one band among 2.4 GHz, 5 GHz, 6 GHz, 60 GHz, and 900 MHz, ormay also operate in other bands.

The present specification relates to a situation in which severalchannels are supported within one BSS. In this case, the STA maytransmit/receive a signal through one or more of the several channels.That is, the AP and/or STA within the BSS may support a plurality ofchannels. The STA may transmit a signal through at least one channelamong the plurality of channels supported by the AP. At least onechannel among the plurality of channels may also be called in variousterms such as a link, a session, a connection, or the like.

An EHT operation element may include operating channel information ofthe AP. The EHT operation element may include information on at leastone channel within a first band in which an EHT standard is supported. AVHT operation element may include information on at least one channelwithin a second band in which a VHT standard is supported. An HToperation element may include an HT operation element includinginformation on at least one channel within a third band in which an HTstandard is supported. According to an embodiment, the first band mayinclude the aforementioned 6 GHz band. The second band may include theaforementioned 5 GHz band. The third band may include the aforementioned2.4 GHz band.

According to an embodiment, when the BSS operates in the 5 GHz and 6 GHzbands, the HT operation element may include 40 MHz channel informationwithin 5 GHz (e.g., information on a primary 20 MHz channel andinformation on a secondary 20 MHz channel). The VHT operation elementmay include an 80 MHz or 160 MHz channel within 5 GHz. The EHT operationelement may include channel information within the 6 GHz band. Forexample, when an AP (or a transmitting STA) uses a channel 42 (80 MHz)and a channel 155 (80 MHz) within a 5 GHz band and uses a channel 7 (80MHz) within a 6 GHz band, information of the channel 7 within the band 6GHz may be included in the EHT operation element. Since a VHT-STA and anHE-STA may operation in a channel within a 5 GHz band of a correspondingBSS, the VHT operation element may include channel information withinthe 5 GHz band in which the VHT-STA and the HE-STA operate. Therefore,information on two channels (the channel 42 and the channel 155) withinthe 5 GHz band may be included in the VHT operation element. Since theHE-STA may operate in the 40 MHz channel within a 5 GHz band of acorresponding BSS, the HE operation element may include information of aband in which the HT-STA can operate. The HE operation element mayinclude primary 20 MHz channel and primary 40 MHz channel informationwithin the 5 GHz band in which the HT-STA operates.

In order to ensure backward compatibility with the existing STA, theEHT-STA may transmit the HT operation element and the VHT operationelement together with the EHT operation element. Therefore, the EHT-STAmay transmit only information not included in the HT operation elementand the VHT operation element to another STA by allowing the EHToperation element to include the information. The informationtransmitted by the EHT-STA by being included in the EHT operationelement may be information which does not overlap with the HT operationelement and VHT operation element. Accordingly, an overhead can bereduced.

FIG. 23 may illustrate a first format of an EHT operation element, andFIG. 24 may illustrate a second format of the EHT operation element.FIG. 23 may illustrate a format for defining information on a band or RFnot included in an operation element (e.g., a VHT operation element oran HR operation element) conforming to the conventional standard bydividing the information for each band or RF. FIG. 24 may illustrate aformat for defining information on all bands or RFs, not included in theoperation element conforming to the conventional standard, at a time.

FIG. 23 illustrates a first format of the EHT operation element.

Specifically, the EHT operation element may include an Element ID field2310, a Length field 2320, or an EHT Operation Information field 2330.The Element ID field 2310 may include information on an element ID. TheLength field 2320 may include information on the number of octets afterthe Length field 2320.

The EHT Operation Information field 2330 may include a Number of Bandfield 2340, a Channel Order field 2350, and/or a Band Info Tuples field2360.

The Number of Band field 2340 may include information on the number ofbands or RFs not included in the VHT operation element among the numbersof all bands or all RFs of a BSS. For example, an AP may use a channel42 (80 MHz) and a channel 155 (80 MHz) within a 5 GHz band, and may usea channel 7 (80 MHz) within a 6 GHz band. The VHT operation element mayinclude information on the channel 42 and the channel 155 within the 5GHz band. Therefore, the EHT operation element may include onlyinformation on one channel 7 within the 6 GHz band. The Number of Bandfield 2340 in the EHT Operation Information field 2330 may have a firstvalue (e.g., {1}).

The Channel Order field 2350 may include information on a location of aprimary channel. The Channel Order field 2350 may indicate theinformation on the location of the primary channel in various manners.For example, the Channel Order field 2350 may indicate a primary 20 MHzchannel within 160 MHz through a bitmap.

The Band Info Tuples field 2360 may include information on each band orRF. Specifically, the Band Info Tuples field 2360 may be configuredrepeatedly to indicate information on the band or RF, except for channelinformation included in the VHT operation element. For example, the APmay transmit information on 2 RFs through the EHT operation element,except for the channel information included in the VHT operationelement. Therefore, the Band Info Tuples field 2360 may be configured bybeing repeated 2 times.

The Band Info Tuples field 2360 may include an Operating Class subfield2370 or a Channel number subfield 2380.

The Operating Class subfield 2370 may include information on anoperating class (or operation class) of each band or RF. It may bedefined that an index indicating one set among sets of rules applied toa wireless device corresponds to one operating class. For example, oneset of the rules may consist of a channel starting frequency, a channelspacing, a channel set, and a behavior limit set. The operating classmay be configured differently for each country. For example, the AP mayuse the channel 42 (80 MHz) and the channel 155 (80 MHz) within the 5GHz band, and may use the channel 7 (80 MHz) within the 6 GHz band. TheVHT operation element may include information of an operating classindicating the channel 42 and the channel 155 within the 5 GHz band.Therefore, the Operating Class subfield 2370 in the Band Info Tuplesfield 2360 may have a value (e.g., {133}) for indicating the 80 MHzchannel within the 6 GHz band.

The Channel number subfield 2380 may include information on a channelnumber of each band or RF. For example, the AP may use the channel 42(80 MHz) and the channel 155 (80 MHz) within the 5 GHz band, and may usethe channel 7 (80 MHz) within the 6 GHz band. The VHT operation elementmay include information on the channel 42 and the channel 155 within the5 GHz band. Therefore, the Channel number subfield 2380 in the Band InfoTuples field 2360 may have a value (e.g., {7}) for indicating thechannel 7.

FIG. 24 illustrates a second format of the EHT operation element.

The EHT operation element may include operating channel information ofan AP. Unlike the first format shown in FIG. 23 , the second format maybe a format for defining information on all bands or RFs, not includedin the VHT operation element, at a time.

An EHT Operation Information field 2430 may include a Band Control field2431, a Channel Order field 2432, a 2.4 GHz Band Info field 2433, a 5GHz Band Info field 2434, or a 6 GHz Band Info field 2435.

The Band Control field 2431 may include information on a band or RF of acurrent BSS, except for channel information included in the VHToperation element. The Band Control field 2431 may include informationon a combination of bands or RFs within 2.4 GHz, 5 GHz or 6 GHz, exceptfor channel information included in the operation element conforming tothe conventional standard. For example, when the BSS operates in 4 RFsand 3 bands, there may be about 50 types of the combination of bands orRFs. A value of the Band Control field 2431 may be configured with alookup table according to the combination of bands or RFs. For example,the value of the Band Control field 2431 may be configured with 8 bits.When the value of the Band Control field 2431 is {2}, that is,{00000010}, it may indicate that 2 RFs are present for the 5 GHz band,and 2 RFs are present for the 6 GHz band. According to an embodiment,the AP may transmit to a receiving STA a mapping relation between the RFand the band through the Band Control field 2431. The receiving STA maydetermine an optimal mapping relation between the RF and the band fromthe AP to communicate with the AP, based on the received mappingrelation between the RF and the band.

The Channel Order field 2432 may include information on a location of aprimary channel. The primary channel may imply a specific frequencydomain in which a beacon (or an extra control frame) can be transmitted.The Channel Order field 2432 may include the information on the locationof the primary channel in various manners. For example, the ChannelOrder field 2432 may indicate a primary 20 MHz channel within 160 MHzthrough a bitmap.

The 2.4 GHz Band Info field 2433 may include information on a 2.4 GHzband. Specifically, the 2.4 GHz Band Info field 2433 may includeinformation on a channel number and information on a channel widthwithin the 2.4 GHz band.

The 5 GHz Band Info field 2434 may include information on a 5 GHz band.Specifically, the 5 GHz Band Info field 2434 may include information ona channel number and information on a channel width within the 5 GHzband.

The 6 GHz Band Info field 2435 may include information on a 6 GHz band.Specifically, the 6 GHz Band Info field 2435 may include information ona channel number and information on a channel width within the 6 GHzband.

Information on a channel number, which is included in the 2.4 GHz BandInfo field 2433, the 5 GHz Band Info field 2434, and the 6 GHz Band Infofield 2435, may include information on a center frequency and channelwidth (or a frequency domain (e.g., 20 MHz)) described in FIG. 9 andFIG. 10 . However, the information on the channel number may be defineddifferently for each country, and may not include information on thechannel width. Therefore, the 2.4 GHz Band Info field 2433, the 5 GHzBand Info field 2434, and the 6 GHz Band Info field 2435 may include notonly the information on the channel number but also the information onthe channel width.

According to an embodiment, the second format of the EHT operationelement may further include information on an operating class in orderto transmit information on a regulation related to a channel (e.g.,transmit (TX) power).

Hereinafter, another format of the EHT operation element will bedescribed.

The EHT operation element may include every operating channelinformation of an AP, unlike in FIG. 23 and FIG. 24 . For example, whenthe AP is currently using a channel 42 (80 MHz) and a channel 155 (80MHz) in a 5 GHz band and a channel 7 (80 MHz) in a 6 GHz band, the EHToperation element may include every information on three 80 MHz channels(240 MHz in total) and two bands (5 GHz and 6 GHz).

The VHT operation element may include information on a band in which theVHT-STA and the HE-STA can operate. Therefore, information included inthe EHT operation element may be included in the VHT operation elementin a partially overlapping manner.

The EHT operation element may be newly configured separately from theVHT operation element or the HT operation element, and thus may supportall combinations of bands or RFs capable of operating in the EHT-STA.For example, when the AP uses three 80 MHz channels in the 5 GHz band oruses three bands of 2.4 GHz, 5 GHz and 6 GHz, the AP may indicateinformation on all channels through the EHT operation element.

FIG. 25 may illustrate a third format of the EHT operation element, andFIG. 26 may illustrate a fourth format of the EHT operation element.FIG. 25 may illustrate a format for defining information on a band or RFby dividing the information for each band or RF. FIG. 26 may illustratea format for defining information on all bands or RFs at a time.

FIG. 25 illustrates a third format of the EHT operation element.

Specifically, the EHT operation element may include an Element ID field2510, a Length field 2520, or an EHT Operation Information field 2530.The Element ID field 2510 may include information on an element ID. TheLength field 2520 may include information on the number of octets afterthe Length field 2520.

The EHT Operation Information field 2530 may include a Number of Bandfield 2540, a Channel Order field 2550, or a Band Info Tuples field2560.

The Number of Band field 2540 may include information on the number ofall bands or all RFs of a BSS. For example, an AP may use a channel 42(80 MHz) and a channel 155 (80 MHz) within a 5 GHz band, and may use achannel 7 (80 MHz) within a 6 GHz band. Since the channel 42 and thechannel 155 are discontinuous in the 5 GHz band, the AP may preferablyinclude 2 RFs. In addition, in order to transmit a signal of the channel7 in the 6 GHz band, the AP may include additional one RF. That is, theAP may include 3 RFs in total. Therefore, the Number of Band field 2540in the EHT Operation Information field 2530 may have a first value(e.g., {3}).

The Channel Order field 2550 may include information on a location of aprimary channel. The Channel Order field 2550 may indicate theinformation on the location of the primary channel in various manners.For example, the Channel Order field 2550 may indicate a primary 20 MHzchannel within 160 MHz through a bitmap.

The Band Info Tuples field 2560 may include information on the number ofbands or RFs. Specifically, the Band Info Tuples field 2560 may beconfigured repeatedly to indicate information on the number of all bandsor RFs. For example, the AP may use a channel 42 (80 MHz) and a channel155 (80 MHz) within the 5 GHz band, and may use a channel 7 (80 MHz)within the 6 GHz band. In order for the AP to use the channel 42 and thechannel 155 within the 5 GHz band and use the channel 7 within the 6 GHzband, 3 RFs may be required. Therefore, the Band Info Tuples field 2560may be configured by being repeated 3 times.

The Band Info Tuples field 2560 may include an Operating Class subfield2570 or a Channel Number subfield 2580.

The Operating Class subfield 2570 may include information on anoperating class of each band or RF. For example, the AP may use thechannel 42 (80 MHz) and the channel 155 (80 MHz) within the 5 GHz band,and may use the channel 7 (80 MHz) within the 6 GHz band. In order forthe AP to use the channel 42 and the channel 155 within the 5 GHz bandand use the channel 7 within the 6 GHz band, 3 RFs may be required.Therefore, the Band Info Tuples field 2560 may be configured by beingrepeated 3 times. The Band Info Tuples field 2560 may include a firstBand Info Tuples field, a second Band Info Tuples field, and a thirdBand Info Tuples field. Therefore, a first Operating Class subfield inthe first Band Info Tuples including information on the channel 42 mayhave a value (e.g., {128}) for indicating an 80 MHz channel within the 5GHz band. A second Operating Class subfield in the second Band InfoTuples including information on the channel 155 may have a value (e.g.,{128}) for indicating an 80 MHz channel within the 5 GHz band. A thirdOperating Class subfield in the third Band Info Tuples includinginformation on the channel 7 may have a value (e.g., {133}) forindicating an 80 MHz channel within the 6 GHz band.

The Channel Number subfield 2580 may include information on a channelnumber of each band or RF. For example, the AP may use the channel 42(80 MHz) and the channel 155 (80 MHz) within the 5 GHz band, and may usethe channel 7 (80 MHz) within the 6 GHz band. The Band Info Tuples field2560 may include a first Band Info Tuples field, a second Band InfoTuples field, and a third Band Info Tuples field. Therefore, a firstChannel number subfield in the first Band Info Tuples field may have avalue (e.g., {42}) for indicating the channel 42 within the 5 GHz band.A second Channel number subfield in the second Band Info Tuples fieldmay have a value (e.g., {155}) for indicating the channel 155 within the5 GHz band. A third Channel number subfield in the third Band InfoTuples field may have a value (e.g., {7}) for indicating the channel 7within the 6 GHz band.

FIG. 26 illustrates a fourth format of the EHT operation element.

The EHT operation element may include operating channel information ofan AP. Unlike the third format shown in FIG. 25 , the fourth format maybe a format for defining information on all bands or RFs at a time.

An EHT Operation Information field 2630 may include a Band Control field2631, a Channel Order field 2632, a 2.4 GHz Band Info field 2633, a 5GHz Band Info field 2634, or a 6 GHz Band Info field 2635.

The Band Control field 2631 may include information on a band or RF of acurrent BSS. The Band Control field 2631 may include information on acombination of bands or RFs within 2.4 GHz, 5 GHz or 6 GHz. For example,when the BSS operates in 4 RFs and 3 bands, there may be about 100 typesof the combination of bands or RFs. A value of the Band Control field2631 may be configured with a lookup table according to the combinationof bands or RFs. For example, the value of the Band Control field 2631may be configured with 8 bits. When the value of the Band Control field2631 is {1}, that is, {00000001}, it may indicate that 2 RFs are presentfor the 5 GHz band, and 2 RFs are present for the 6 GHz band. As anotherexample, when the value of the Band Control field 2631 is {5}, i.e.,{00000101}, it may indicate that one RF is present for the 5 GHz band,and 3 RFs are present for the 6 GHz band.

The Channel Order field 2632 may correspond to the Channel Order field2432 of FIG. 24 .

The 2.4 GHz Band Info field 2633, the 5 GHz Band Info field 2634, andthe 6 GHz Band Info field 2635 may correspond to the 2.4 GHz Band Infofield 2433, the 5 GHz Band Info field 2434, and the 6 GHz Band Infofield 2435 of FIG. 24 .

Second Embodiment

A second embodiment described hereinafter relates to a technical featurethat can be performed together with the first embodiment. For example,information described hereinafter may be transmitted/received togetherwhile transmitting/receiving at least any one of the plurality of fieldsof FIG. 23 to FIG. 26 described in the first embodiment. In addition, atleast any one of the plurality of fields of FIG. 23 to FIG. 26 describedin the first embodiment may be transmitted/received within a configuredperiod (e.g., a service period (SP)) according to the second embodiment.

Description on AP

An AP of the present specification may be described in various manners.

The AP may be described in such a manner that a first RF supporting afirst band/link, a second RF supporting a second band/link, and/or athird RF supporting a third band/link are included in one device. Thatis, it may be described in such a manner that one AP is configured, andthe AP supports several bands/links.

The AP may be described in another manner. For example, the AP may bedescribed in such a manner that first to third APs are included in onedevice. The first AP may transmit/receive a signal of a first band. Thesecond AP may transmit/receive a signal of a second band. The third APmay transmit/receive a signal of a third band. The first AP, the secondAP, and/or the third AP may be co-located in one device. In addition,the first AP, the second AP, and/or the third AP may be configured asone-chip. In addition, the first AP, the second AP, and/or the third APmay be controlled by one processor, and control information applied toany one AP may also be shared with another AP by means of the processor.

In summary, an AP supporting a plurality of bands or links may beexpressed as one AP or a set of a plurality of APs. For convenience ofexplanation, hereinafter, in the present specification, the APsupporting the plurality of bands/links will be described by beingclassified into a first AP, a second AP, a third AP, or the like.However, since the first AP, the second AP, and the third AP are used toidentify an operational band or link, the “first to third APs” used inthe second embodiment described below may be referred to as an AP.

Basic Operation for Second Embodiment

In an embodiment of the present specification, an operation in which thefirst AP provides an STA with information of the second AP may beproposed. The first AP may operate in a first band. The second AP mayoperate in a second band. For example, the first band may include a 2.4GHz band and/or a 5 GHz band. The second band may include a 6 GHz band.

The second AP may prohibit an EDCA of an STA associated with the secondAP. In a BSS in which the EDCA is prohibited, an access method foruplink communication may be limited only to UL MU communication based ona trigger frame. The STA may be allocated a resource through the triggerframe. The STA may transmit a signal (or data) only when the resource isallocated. In addition, the STA may transmit a signal (or data) only inan OFDMA random access, based on the trigger frame.

In addition, in the BSS in which the EDCA is prohibited, active scanningmay be prohibited in the STA. In this case, the STA may not be able totransmit a probe request frame in which a broadcast address is set.Instead, the STA may discover the second AP through passive scanning forreceiving a beacon (or a beacon frame). In addition, the STA may alsodiscover the second AP through a probe request frame in which a unicastaddress is set.

When the EDCA of the STA is prohibited and interference caused by OBSSis not severe, a contention overhead may be minimized. In addition, whenthe EDCA of the STA is prohibited and interference caused by OBSS is notsevere, collision may not occur. When the EDCA of the STA is prohibited,the AP may control both DL transmission and UL transmission, so thatefficient resource distribution can be achieved and performance can beoptimized. However, a feedback process for UL transmission of the STAmay be considered. When the feedback process is frequently performed inthe STA and a lot of information is included in the feedback, the AP mayaccurately know a current situation (or state) of the STA. When the APaccurately knows the current situation (or state), the AP may optimize aresource. However, in this case, an overhead may be increased. Inaddition, if a feedback count and information included in the feedbackare decreased to reduce the overhead, it may be difficult to performresource allocation optimized in the AP.

When the EDCA of the STA is prohibited, the STA may perform UL feedbackonly when the AP transmits a trigger frame. Therefore, when there is achange in traffic to be transmitted by the STA or a current resourceallocation level is not appropriate, it may be difficult for the STA tocompensate for the problem. A method of performing the feedback based onthe OFDMA random access may be able to compensate for the problem above.However, the method of performing the feedback based on the OFDMA randomaccess may be performed when the AP properly allocates a resource forthe OFDMA random access. According to an embodiment, it may be difficultfor the AP to predict the OFDMA random access of the STA. It may bedifficult for the AP to properly allocate a resource to each STA.

In addition, when UL data transmission of the current STA is sensitiveto a latency, the AP shall allocate the resource according to thelatency of the STA. However, when the AP cannot allocate the resourceaccording to the latency of the STA, the STA may solve this through theEDCA. When a UL data frame is very short, the STA may transmit a UL dataframe directly to the AP without having to be allocated a resourcethrough a feedback. When the STA transmits the UL data frame through theabove scheme, an overhead may be reduced.

Therefore, in the BSS in which the EDCA is prohibited, it may beimportant that the feedback is achieved efficiently and rapidly. It mayalso be important to decrease a delay even when the STA first performsan association process with respect to the AP.

The present specification may propose a method in which the first APoperating in the first band (the 2.4 GHz band or the 5 GHz band)provides the second AP operating in the second band (the 6 GHz band)with UL resource allocation information for a feedback, UL datatransmission, association process, or the like.

The STA may be associated with the first AP operating in the first band(the 2.4 GHz and or the 5 GHz band). The STA may obtain (or receive)information on the second AP operating in the second band (the 6 GHzband) from the first AP. In this case, the information on the second APmay be included in a neighbor report element. The neighbor reportelement may be used when transferring neighboring BSS information. Theneighbor report element may include information on a BSSID, a BSSchannel, a PHY type, an AP capability, or a beacon period.

However, the neighbor report element may not be able to represent everyinformation on a current BSS situation or a BSS operation. Therefore, inthe BSS in which the EDCA is prohibited, performance may be optimizedwhen information on a feedback process or association process isprovided in advance to the STA.

According to an embodiment, the STA may not be provided in advance withthe information on the feedback process or association process. The STAmay move from the first band (the 2.4 GHz or the 5 GHz band) to thesecond band (the 6 GHz band). That is, the STA may change a connectionwith the first AP to a connection with the second AP. In this case,since the STA cannot directly be associated with the second AP, anassociation operation may be performed with respect to the second APafter waiting for a specific period of time. In addition, the STA maywait for an unspecified period of time to perform the feedback. Even ifthe STA waits for the unspecified period of time to perform thefeedback, the STA may be short of a feedback resource. In this case,when the STA operates in the first band, performance may be moredecreased than when the STA operates in the second band.

In the BSS in which the EDCA is prohibited, the STA may transmit asignal (or data) only when a resource is allocated by using a triggerframe. The trigger frame may allocate a resource which can betransmitted exclusively by the STA and a resource which can contendthrough an OFDMA random access. In order for the STA to perform thefeedback operation or the association operation, the STA may needresource information for the OFDMA random access. That is, the STA mayneed the trigger frame including the resource information.

Accordingly, hereinafter, a specific operation for allocating a resourcethrough a trigger frame will be described in a multi-link situation.

Specific Operation for Second Embodiment

A second embodiment of the present specification may propose a method oftransmitting/receiving a signal (or data) in a transmitting STA (or AP)and/or a receiving STA, by using a target wake time (TWT) element (e.g.,a broadcast TWT element).

A target wake time technology is defined as a power save technology ofthe IEEE 802.11ah standard. That is, the target wake time technology canreduce power consumption of the transmitting STA (or AP) or thereceiving STA in a BSS. The target wake time technology has beenextended to an individual TWT/broadcast TWT technology in the IEEE802.11ax standard.

According to a broadcast TWT technology, in order to transmit/receivebuffered data with respect to an unspecified STA among STAs operating atlow power, the transmitting STA (or AP) may transmit a trigger frameincluding an OFDMA random access resource. In order to reduceunnecessary power consumption of a low-power STA, a broadcast TWTelement of a beacon frame may include information such as a transmissiontiming or the like of the trigger frame.

According to a second embodiment of the present specification, thereceiving STA may obtain information for performing communication in thesecond link from the transmitting STA through the first link. Thereceiving STA may perform communication with the transmitting STAthrough the second link, based on the information for performingcommunication in the second link. The transmitting STA may include afirst AP supporting the first link and a second AP supporting the secondlink. The first AP and the second AP may be co-located to operate, andmay be configured as one-chip.

The first link or the second link may be included within a 2.4 GHz, 5GHz, or 6 GHz band. For example, the first link may be received througha first band (e.g., 2.4 GHz or 5 GHz). The second link may be receivedthrough a second band (a 6 GHz band) different from the first band.

The receiving STA which supports a multi-link including the first linkand the second link may receive a target wake time (TWT) element (e.g.,a broadcast TWT element) through the first link. The receiving STA maysupport the multi-link including the first link and the second link.That is, the receiving STA may transmit/receive a signal (or data)through the first link and/or the second link. The receiving STA mayestablish a connection with respect to the transmitting STA through thefirst link and/or the second link.

The receiving STA may receive a TWT element through the first link. TheTWT element may be included in a beacon (or a beacon frame). That is,the receiving STA may receive the TWT element through the beacon.

The TWT element may include information for configuring a TWT period forthe second link. The TWT period may be called a service period (SP). Forexample, the TWT element may include information on a length of the TWTperiod and/or a timing at which the trigger is transmitted in thetransmitting STA. As another example, the TWT element may includeinformation related to a target wake time, information related to anominal minimum TWT wake duration, information related to a TWT wakeinterval mantissa, information related to a broadcast TWT persistenceexponent/mantissa, and/or information related to a broadcast TWT ID.

The receiving STA may change an operational mode of the receiving STAfrom a first mode to a second mode, in response to the beacon. The firstmode may include an awake mode. The second mode may include a doze mode.The receiving STA may operate in the second mode, before receiving thebeacon. When receiving the beacon, the receiving STA may change theoperational mode from the second mode to the first mode. Therefore, thereceiving STA may receive the beacon in the first mode. The receivingSTA may change again the operational mode of the receiving STA from thefirst mode to the second mode, in response to the beacon (or afterreceiving the beacon).

The receiving STA may configure a TWT period for the second link, basedon the TWT element. Since the TWT element includes information forconfiguring the TWT period for the second link, based on this, thereceiving STA may configure the TWT period for the second link. Thereceiving STA may change the operational mode from the second mode tothe first mode before the TWT period for the second link starts.Therefore, the receiving STA may operate in the first mode within theTWT period.

The receiving STA may perform communication with the transmitting STAthrough the second link within the TWT period. Specifically, thereceiving STA may receive the trigger frame from the transmitting STAthrough the second link. The receiving STA may be allocated a resourcethrough the trigger frame. The receiving STA may transmit/receive asignal (or data) through the allocated resource.

According to an embodiment, the TWT element may include information forconfiguring the TWT period for the first link and/or second link. Thereceiving STA may configure the TWT period for the first link, the TWTperiod for the second link, and/or the TWT period for the first link andsecond link, based on the TWT element. For example, when the receivingSTA configures the TWT period for the first link and second link, thereceiving STA may perform communication with the transmitting STAthrough the first link and/or the second link within the TWT period.

The aforementioned operation of the transmitting STA and receiving STAmay be illustrated through a specific example in FIG. 27 .

FIG. 27 illustrates an example of a TWT procedure.

Referring to FIG. 27 , the aforementioned transmitting STA may berelated to an AP 2700. The aforementioned receiving STA may be relatedto an STA1 2701.

The AP 2700 may perform a target beacon transmission time (TBTT)negotiation procedure with respect to the STA1 2701. Specifically, theSTA1 2701 may transmit a TWT request frame to the AP 2700. The AP 2700may transmit a TWT response frame, in response to the TWT request frame.The TWT response frame may include information for allocating abroadcast TWT ID. The TBTT negotiation procedure may be optional.

Thereafter, the AP 2700 may transmit a beacon 2710. The beacon 2710 mayinclude a broadcast TWT element. The broadcast TWT element may includeinformation on a service period (SP) 2720. Specifically, the broadcastTWT element may include information related to a target wake time,information related to a nominal minimum TWT wake duration, informationrelated to a TWT wake interval mantissa, information related to abroadcast TWT persistence exponent/mantissa, and/or information relatedto a broadcast TWT ID. The information may be described below in greaterdetail with reference to FIG. 28 to FIG. 30 .

According to an embodiment, the beacon 2710 may be transmitted through afirst link. The beacon 2710 may include information related to the SP2720 for a second link. Through the first link, the AP 2700 may transmitinformation for configuring the SP 2720 in the second link to the STA12701 or an STA2 2702 through the beacon 2710.

According to an embodiment, the beacon 2710 may include informationrelated to the SP 2720 for the first link. The AP 2700 may transmitinformation for configuring the SP 2720 in the first link to the STA12701 or the STA2 2702 through the beacon 2710.

According to an embodiment, the beacon 2710 may also include informationrelated to the SP 2710 for a multi-link in which the first link and thesecond link are aggregated. The AP 2700 may transmit information forconfiguring the SP 2720 in the multi-link to the STA1 2701 or the STA22702 through the beacon 2710.

The AP 2700 may transmit a trigger frame within the SP 2720. The AP 2700may transmit the trigger frame, in order to receive data buffered in theSTA (the STA1 2701 or the STA2 2702). The trigger frame may include anOFDMA random access resource. The STA1 2701 or the STA2 2702 mayexchange data with the AP 2700, based on the trigger frame.

FIG. 28 to FIG. 30 illustrate a frame format of a TWT element.

Referring to FIG. 28 to FIG. 30 , a first AP operating in a first band(a 2.4 GHz or 5 GHz band) may provide an STA with a broadcast TWTelement 2800 of a second AP operating in a second band (a 6 GHz band).The broadcast TWT element 2800 may include information related to atarget wake time, information related to a nominal minimum TWT wakeduration, information related to a TWT wake interval mantissa,information related to a broadcast TWT persistence exponent/mantissa,and/or information related to a broadcast TWT ID.

The broadcast TWT element 2800 may include an element ID field 2810, alength field 2820, a control field 2830, and/or a TWT parameterinformation field 2840.

The element ID field 2810 may include information on an element ID. Thelength field 2820 may include information on the number of octets afterthe length field 2820. The control field 2830 may include information ona TWT control. For example, the information on the TWT control mayinclude information on a null data PPDU (NDP) paging indicator,information indicating that it is a broadcast TWT element, and/orinformation on whether a TWT information frame is deactivated, or thelike.

The TWT parameter information field 2840 may include a request typefield 2910, a target wake time field 2920, a nominal minimum TWT wakeduration field 2930, a TWT wake interval mantissa field 2940, and/or abroadcast TWT Info field 2950.

The request type field 2910 may include information on whether it is aTWT request STA or a TWT response STA and/or information on a type of aTWT command.

The target wake time field 2920 may include information on a timing atwhich a first trigger frame is transmitted based on a beacon. Forexample, referring to FIG. 27 , the target wake time field 2920 mayinclude information on a timing at which a trigger frame within the SP2720, as a first trigger frame, is transmitted after the beacon 2710.

The nominal minimum TWT wake duration field 2920 may include lengthinformation of a service period to be allocated by the trigger frame.For example, referring to FIG. 27 , the nominal minimum TWT wakeduration field 2920 may include length information of the SP 2720.

The TWT wake interval mantissa field 2930 may include information on aninterval by which a second trigger frame is transmitted after the firsttrigger frame within a service period (SP).

The broadcast TWT Info field 2950 may include a broadcast TWTpersistence exponent field 3010, a broadcast TWT ID field 3020, and/or abroadcast TWT persistence mantissa field 3030.

The broadcast TWT persistence exponent field 3010 and/or the broadcastTWT persistence mantissa field 3030 may include information on a periodin which corresponding broadcast TWT information persists. That is, thebroadcast TWT persistence exponent field 3010 and/or the broadcast TWTpersistence mantissa field 3020 may include information on unit ofperiodicity of a beacon. In other words, the persistence mantissa field3020 may include information on a time during which information includedin a broadcast TWT element is valid. For example, the persistencemantissa field 3020 may include information on the number of beaconsduring which the information included in the broadcast TWT element isvalid.

The broadcast TWT ID field 3020 may include information on acorresponding broadcast TWT ID. For example, when a broadcast TWTelement is transmitted to all STAs, the broadcast TWT ID field 3020 mayhave a first value (e.g., {0}). As another example, when the broadcastTWT element is transmitted to only a specific STA, the broadcast TWT IDfield 3020 may have a second value (e.g., {1}). When the broadcast TWTelement is transmitted only to the specific STA, the specific STA may beallocated a resource through a trigger frame, and may performcommunication through the allocated resource.

In the present specification, regarding the aforementioned broadcast TWTinformation, it may be proposed that the first AP operating in the firstband (the 2.4 GHz or 5 GHz band) provides the STA with the entirety orpart of the broadcast TWT information of the second AP operating in thesecond band (the 6 GHz band). The broadcast TWT information may beincluded in the broadcast TWT element.

If the entirety of the broadcast TWT information is provided to the STA,the first AP may transmit the entirety of the broadcast TWT element(e.g., the broadcast TWT element 2800 of FIG. 28 ).

If the part of the broadcast TWT information is provided to the STA, thefirst AP may transmit the part of the broadcast TWT information to theSTA through a new element distinct from the broadcast TWT element. Ifthe part of the broadcast TWT information is provided to the STA, thefirst AP may transmit the part of the broadcast TWT information to theSTA by including it to the neighbor report element.

The part of the broadcast TWT information may include information ontarget wake time. The remaining information, excluding the informationon target wake time from the broadcast TWT information, may be added oromitted.

When the entirety of the broadcast TWT element is transmitted to theSTA, a field for determining whether information included in thebroadcast TWT element is information on a currently associated AP orinformation on a currently un-associated AP may be required. Therefore,a reserved bit of a control field may include information fordetermining whether it is the information on the currently associated APor the information on the currently un-associated AP.

For example, the first AP operating in the first band (e.g., the 2.4 or5 GHz band) may be the currently associated AP. The second AP operatingin the second band (e.g., the 6 GHz band) may be the currentlyun-associated AP. In this case, the broadcast TWT element may includeinformation for determining whether the information included in thebroadcast TWT element is the information on the currently associatedfirst AP or the information on the currently un-associated second AP.For example, the reserved bit of the control field included in thebroadcast TW element may include information for determining whether theinformation included in the broadcast TWT element is the information onthe first AP or the information on the second AP. If the reserved bit ofthe control field has a first value {0}, the broadcast TWT element mayinclude the information on the first AP. If the reserved bit of thecontrol field has a second value {1}, the broadcast TWT element mayinclude the information on the second AP.

As another example, the reserved bit may be further used to set a bitfor each band. The reserved bit may include information on whether it isthe first AP operating in the first band (the 2.4 GHz band), the secondAP operating in the second band (the 6 GHz band), or the third APoperating in the third band (the 5 GHz band).

FIG. 31 is a flowchart for describing an exemplary operation of atransmitting STA.

Referring to FIG. 31 , in step S3110, the transmitting STA (or AP)(e.g., the AP 2700 of FIG. 27 ) may transmit a target wake time (TWT)element (e.g., the broadcast TWT element 2800 of FIG. 28 ) through afirst link. The TWT element may be included in a beacon (or a beaconframe). That is, the transmitting STA may transmit the TWT elementthrough the beacon.

The TWT element may include information for configuring a TWT period(e.g., the SP 2720 of FIG. 27 ) for the second link. For example, theTWT element may include information on a length of the TWT period and/ora timing at which the trigger is transmitted in the transmitting STA. Asanother example, the TWT element may include information related to atarget wake time, information related to a nominal minimum TWT wakeduration, information related to a TWT wake interval mantissa,information related to a broadcast TWT persistence exponent/mantissa,and/or information related to a broadcast TWT ID.

In step S3120, the transmitting STA may configure a TWT period for thesecond link, based on the TWT element. Since the TWT element includesinformation for configuring the TWT period for the second link, based onthis, the transmitting STA may configure the TWT period for the secondlink. Specifically, after a beacon is transmitted through the firstlink, the transmitting STA may configure the TWT period by transmittinga trigger frame through the second link. The TWT period may be called aservice period (SP).

In step S3130, the transmitting STA may perform communication with areceiving STA (e.g., the STA1 2701 of FIG. 27 ) through the second linkwithin the TWT period. The transmitting STA may allocate a resource forperforming communication with the receiving STA through the triggerframe. The resource may be allocated in the second link. Thetransmitting STA may perform communication through the allocatedresource with respect to the receiving STA.

Thereafter, the transmitting STA may transmit a second trigger framethrough the second link. The transmitting STA may configure a second TWTperiod for the second link through the second trigger frame. Thetransmitting STA may perform communication with the receiving STA withinthe second TWT period.

FIG. 32 is a flowchart for describing an exemplary operation of areceiving STA.

Referring to FIG. 32 , in step S3210, the receiving STA (e.g., the STA12701 of FIG. 27 ) may receive a target wake time (TWT) element (e.g.,the broadcast TWT element 2800 of FIG. 28 ) through a first link. TheTWT element may be included in a beacon (or a beacon frame). That is,the receiving STA may receive the TWT element through the beacon.

The TWT element may include information for configuring a TWT period(e.g., the SP 2720 of FIG. 27 ) for the second link. For example, theTWT element may include information on a length of the TWT period and/ora timing at which the trigger is transmitted in the transmitting STA. Asanother example, the TWT element may include information related to atarget wake time, information related to a nominal minimum TWT wakeduration, information related to a TWT wake interval mantissa,information related to a broadcast TWT persistence exponent/mantissa,and/or information related to a broadcast TWT ID.

In step S3220, the receiving STA may configure a TWT period for thesecond link, based on the TWT element. Since the TWT element includesinformation for configuring the TWT period for the second link, based onthis, the receiving STA may configure the TWT period for the secondlink. Specifically, after a beacon is transmitted, the receiving STA mayconfigure the TWT period by receiving a trigger frame. The TWT periodmay be called a service period (SP).

In step S3230, the receiving STA may perform communication with thetransmitting STA (e.g., the AP 2700 of FIG. 27 ) through the second linkwithin the TWT period. A resource for performing communication with thetransmitting STA through the trigger frame received from thetransmitting STA may be allocated to the receiving STA. The resource maybe allocated in the second link. The receiving STA may performcommunication through the allocated resource with respect to thetransmitting STA.

Thereafter, the receiving STA may receive a second trigger frame throughthe second link. The receiving STA may configure a second TWT period forthe second link through the second trigger frame. The receiving STA mayperform communication with the transmitting STA within the second TWTperiod.

FIG. 33 illustrates a transmitting STA or a receiving STA to which anexample of the present disclosure is applied.

Referring to FIG. 33 , the STA 3300 may include a processor 3310, amemory 3320, and a transceiver 3330. The features of FIG. 33 may beapplied to a non-AP STA or an AP STA. The illustrated processor, memory,and transceiver may be implemented as separate chips, or at least two ormore blocks/functions may be implemented through a single chip.

The illustrated transceiver 3330 performs a signaltransmission/reception operation. Specifically, the transceiver 3330 maytransmit and receive IEEE 802.11 packets (e.g., IEEE802.11a/b/g/n/ac/ax/be, etc.).

The processor 3310 may implement the functions, processes, and/ormethods proposed in the present disclosure. Specifically, the processor3310 may receive a signal through the transceiver 3330, process thereceived signal, generate a transmission signal, and perform control forsignal transmission.

The processor 3310 may include an application-specific integratedcircuit (ASIC), another chipset, a logic circuit, and a data processingdevice. The memory 3320 may include read-only memory (ROM), randomaccess memory (RAM), flash memory, memory card, storage medium, and/orother storage device.

The memory 3320 may store a signal (i.e., a reception signal) receivedthrough the transceiver and may store a signal (i.e., a transmissionsignal) to be transmitted through the transceiver. That is, theprocessor 3310 may acquire the received signal through the memory 3320and store the signal to be transmitted in the memory 3320.

FIG. 34 illustrates another example of a detailed block diagram of atransceiver. Some or all blocks of FIG. 34 may be included in theprocessor 3310. Referring to FIG. 34 , a transceiver 3400 includes atransmission part 3401 and a reception part 3402. The transmission part3401 includes a discrete Fourier transform (DFT) unit 3411, a subcarriermapper 3412, an IDFT/(inverse fast Fourier transform) IFFT unit 3413, aCP insertion unit 3414, and a wireless transmission unit 3415. Thetransmission part 3401 may further include a modulator. In addition, forexample, the transmission part 3401 may further include a scramble unit(not shown), a modulation mapper (not shown), a layer mapper (notshown), and a layer permutator (not shown), and these components may bearranged before the DTF unit 3411. That is, in order to prevent anincrease in a peak-to-average power ratio (PAPR), the transmission part3401 allows information to first go through first the DFT unit 3411before mapping a signal to a subcarrier. After a signal spread by theDFT unit 3411 (or precoded in the same sense) is mapped through thesubcarrier mapper 3412, the mapped signal goes through the IDTF/IFFTunit 3413 so as to be generated as a signal on a time axis.

The DFT unit 3411 performs DFT on input symbols and outputscomplex-valued symbols. For example, when Ntx symbols are input (here,Ntx is a natural number), a DFT size is Ntx. The DFT unit 3411 may bereferred to as a transform precoder. The subcarrier mapper 3412 maps thecomplex-valued symbols to each subcarrier in a frequency domain. Thecomplex symbols may be mapped to resource elements corresponding to aresource block allocated for data transmission. The subcarrier mapper3412 may be referred to as a resource element mapper. The IDFT/IFFT unit3413 performs IDFT/IFFT on an input symbol and outputs a baseband signalfor data as a time domain signal. The CP insertion unit 3414 copies arear part of the base band signal for data and inserts it into a frontpart of the base band signal for data. Inter-symbol interference (ISI)and inter-carrier interference (ICI) may be prevented through CPinsertion, so that orthogonality may be maintained even in a multipathchannel.

Meanwhile, the receiving part 3402 includes a wireless reception unit3421, a CP removal unit 3422, an FFT unit 3423, an equalization unit3424, and the like. The wireless reception unit 3421, the CP removingunit 3422, and the FFT unit 3423 of the receiving part 3402 performreverse functions of the wireless transmission unit 3415, the CPinserting unit 3414, and the IFF unit 3413 of the transmitting part3401. The receiving part 3402 may further include a demodulator.

In addition to the illustrated blocks, the transceiver of FIG. 34 mayinclude a reception window controller (not shown) extracting a part of areceived signal and a decoding operation processing unit (not shown)performing a decoding operation on a signal extracted through areception window.

The foregoing technical features of this specification are applicable tovarious applications or business models. For example, the foregoingtechnical features may be applied for wireless communication of a devicesupporting artificial intelligence (AI).

Artificial intelligence refers to a field of study on artificialintelligence or methodologies for creating artificial intelligence, andmachine learning refers to a field of study on methodologies fordefining and solving various issues in the area of artificialintelligence. Machine learning is also defined as an algorithm forimproving the performance of an operation through steady experiences ofthe operation.

An artificial neural network (ANN) is a model used in machine learningand may refer to an overall problem-solving model that includesartificial neurons (nodes) forming a network by combining synapses. Theartificial neural network may be defined by a pattern of connectionbetween neurons of different layers, a learning process of updating amodel parameter, and an activation function generating an output value.

The artificial neural network may include an input layer, an outputlayer, and optionally one or more hidden layers. Each layer includes oneor more neurons, and the artificial neural network may include synapsesthat connect neurons. In the artificial neural network, each neuron mayoutput a function value of an activation function of input signals inputthrough a synapse, weights, and deviations.

A model parameter refers to a parameter determined through learning andincludes a weight of synapse connection and a deviation of a neuron. Ahyperparameter refers to a parameter to be set before learning in amachine learning algorithm and includes a learning rate, the number ofiterations, a mini-batch size, and an initialization function.

Learning an artificial neural network may be intended to determine amodel parameter for minimizing a loss function. The loss function may beused as an index for determining an optimal model parameter in a processof learning the artificial neural network.

Machine learning may be classified into supervised learning,unsupervised learning, and reinforcement learning.

Supervised learning refers to a method of training an artificial neuralnetwork with a label given for training data, wherein the label mayindicate a correct answer (or result value) that the artificial neuralnetwork needs to infer when the training data is input to the artificialneural network. Unsupervised learning may refer to a method of trainingan artificial neural network without a label given for training data.Reinforcement learning may refer to a training method for training anagent defined in an environment to choose an action or a sequence ofactions to maximize a cumulative reward in each state.

Machine learning implemented with a deep neural network (DNN) includinga plurality of hidden layers among artificial neural networks isreferred to as deep learning, and deep learning is part of machinelearning. Hereinafter, machine learning is construed as including deeplearning.

The foregoing technical features may be applied to wirelesscommunication of a robot.

Robots may refer to machinery that automatically process or operate agiven task with own ability thereof. In particular, a robot having afunction of recognizing an environment and autonomously making ajudgment to perform an operation may be referred to as an intelligentrobot.

Robots may be classified into industrial, medical, household, militaryrobots and the like according uses or fields. A robot may include anactuator or a driver including a motor to perform various physicaloperations, such as moving a robot joint. In addition, a movable robotmay include a wheel, a brake, a propeller, and the like in a driver torun on the ground or fly in the air through the driver.

The foregoing technical features may be applied to a device supportingextended reality.

Extended reality collectively refers to virtual reality (VR), augmentedreality (AR), and mixed reality (MR). VR technology is a computergraphic technology of providing a real-world object and background onlyin a CG image, AR technology is a computer graphic technology ofproviding a virtual CG image on a real object image, and MR technologyis a computer graphic technology of providing virtual objects mixed andcombined with the real world.

MR technology is similar to AR technology in that a real object and avirtual object are displayed together. However, a virtual object is usedas a supplement to a real object in AR technology, whereas a virtualobject and a real object are used as equal statuses in MR technology.

XR technology may be applied to a head-mount display (HMD), a head-updisplay (HUD), a mobile phone, a tablet PC, a laptop computer, a desktopcomputer, a TV, digital signage, and the like. A device to which XRtechnology is applied may be referred to as an XR device.

What is claimed is:
 1. A method in a wireless local area network (WLAN)system, the method comprising: transmitting, by a station (STA)multi-link device (MLD) supporting a plurality of links including afirst link and a second link, an association request frame including alink identification (ID) information field related to the plurality oflinks to an access point (AP) MLD; receiving, by the STA MLD, a targetwake time (TWT) element through the first link from the AP MLD, whereinthe TWT element includes a request type field, a TWT control field forconfiguring a nominal minimum TWT wake duration, and a link ID controlfield indicating at least one link to which the TWT element applies,wherein the request type field includes a TWT request subfield relatedto whether the TWT element is transmitted by a TWT requesting STA or aTWT responding STA, wherein the request type field has a length of twooctets, and the TWT control field has a length of one octet; andapplying, by the STA MLD, the TWT element to the at least one linkindicated by the link ID control field.
 2. The method of claim 1,wherein the first link is configured based on one of a 2.4 GHz band, a 5GHz band, and/or a 6 GHz band.
 3. The method of claim 1, wherein thesecond link is configured based on one of a 2.4 GHz band, a 5 GHz band,and/or a 6 GHz band.
 4. The method of claim 1, wherein the STA MLDincludes a first STA operating in the first link and a second STAoperating in the second link.
 5. A method in a wireless local areanetwork (WLAN) system, the method comprising: receiving, by an accesspoint (AP) multi-link device (MLD) supporting a plurality of linksincluding a first link and a second link, an association request frameincluding a link identification (ID) information field related to theplurality of links from a station (STA) MLD; transmitting, by the APMLD, a target wake time (TWT) element through the first link to the STAMLD, wherein the TWT element includes a request type field, a TWTcontrol field for configuring a nominal minimum TWT wake duration, and alink ID control field indicating at least one link to which the TWTelement applies, wherein the request type field includes a TWT requestsubfield related to whether the TWT element is transmitted by a TWTrequesting STA or a TWT responding STA, wherein the request type fieldhas a length of two octets, and the TWT control field has a length ofone octet; and performing, by the AP MLD, a TWT operation with the STAMLD through the at least one link indicated by the link ID controlfield.
 6. The method of claim 5, wherein the first link is configuredbased on one of a 2.4 GHz band, a 5 GHz band, and/or a 6 GHz band. 7.The method of claim 5, wherein the second link is configured based onone of a 2.4 GHz band, a 5 GHz band, and/or a 6 GHz band.
 8. The methodof claim 5, wherein the AP MLD includes a first AP operating in thefirst link and a second AP operating in the second link.
 9. A station(STA) multi-link device (MLD) in a wireless local area network (WLAN)system, the STA MLD comprising: a transceiver adapted to supportplurality of links including a first link and a second link; and aprocessor adapted to control the transceiver, wherein the processor isfurther adapted to: transmit an association request frame including alink identification (ID) information field related to the plurality oflinks to an access point (AP) MLD; receive a target wake time (TWT)element through the first link from the AP MLD, wherein the TWT elementincludes a request type field, a TWT control field for configuring anominal minimum TWT wake duration, and a link ID control fieldindicating at least one link to which the TWT element applies, whereinthe request type field includes a TWT request subfield related towhether the TWT element is transmitted by a TWT requesting STA or a TWTresponding STA, wherein the request type field has a length of twooctets, and the TWT control field has a length of one octet; and applythe TWT element to the at least one link indicated by the link IDcontrol field.
 10. The STA MLD of claim 9, wherein the first link isconfigured based on one of a 2.4 GHz band, a 5 GHz band, and/or a 6 GHzband.
 11. The STA MLD of claim 9, wherein the second link is configuredbased on one of a 2.4 GHz band, a 5 GHz band, and/or a 6 GHz band. 12.The STA MLD of claim 9, wherein the STA MLD includes a first STAoperating in the first link and a second STA operating in the secondlink.
 13. An access point (AP) multi-link device (MLD) in a wirelesslocal area network (WLAN) system, the AP MLD comprising: a transceiveradapted to support plurality of links including a first link and asecond link; and a processor adapted to control the transceiver, whereinthe processor is further adapted to: receive an association requestframe including a link identification (ID) information field related tothe plurality of links from a station (STA) MLD; transmit a target waketime (TWT) element through the first link to the STA MLD, wherein theTWT element includes a request type field, a TWT control field forconfiguring a nominal minimum TWT wake duration, and a link ID controlfield indicating at least one link to which the TWT element applies,wherein the request type field includes a TWT request subfield relatedto whether the TWT element is transmitted by a TWT requesting STA or aTWT responding STA, wherein the request type field has a length of twooctets, and the TWT control field has a length of one octet; and performa TWT operation with the STA MLD through the at least one link indicatedby the link ID control field.
 14. The AP MLD of claim 13, wherein thefirst link is configured based on one of a 2.4 GHz band, a 5 GHz band,and/or a 6 GHz band.
 15. The AP MLD of claim 13, wherein the second linkis configured based on one of a 2.4 GHz band, a 5 GHz band, and/or a 6GHz band.
 16. The AP MLD of claim 13, wherein the AP MLD includes afirst AP operating in the first link and a second AP operating in thesecond link.